Re: [PATCH v2 10/14] serial: pic32_uart: Add PIC32 UART driver

From: Andy Shevchenko
Date: Sun Dec 20 2015 - 11:13:49 EST

On Tue, Dec 15, 2015 at 12:42 AM, Joshua Henderson
<joshua.henderson@xxxxxxxxxxxxx> wrote:
> From: Andrei Pistirica <andrei.pistirica@xxxxxxxxxxxxx>
>
> This adds UART and a serial console driver for Microchip PIC32 class
> devices.
>
> Signed-off-by: Andrei Pistirica <andrei.pistirica@xxxxxxxxxxxxx>
> Signed-off-by: Joshua Henderson <joshua.henderson@xxxxxxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> ---
> drivers/tty/serial/Kconfig | 21 +
> drivers/tty/serial/Makefile | 1 +
> drivers/tty/serial/pic32_uart.c | 927 ++++++++++++++++++++++++++++++++++++++
> drivers/tty/serial/pic32_uart.h | 198 ++++++++
> include/uapi/linux/serial_core.h | 3 +
> 5 files changed, 1150 insertions(+)
> create mode 100644 drivers/tty/serial/pic32_uart.c
> create mode 100644 drivers/tty/serial/pic32_uart.h
>
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index f38beb2..8853b1e 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -901,6 +901,27 @@ config SERIAL_SGI_L1_CONSOLE
> controller serial port as your console (you want this!),
> say Y. Otherwise, say N.
>
> +config SERIAL_PIC32
> + tristate "Microchip PIC32 serial support"
> + depends on MACH_PIC32
> + select SERIAL_CORE
> + help
> + If you have a PIC32, this driver supports the serial ports.
> +
> + Say Y or M to use PIC32 serial ports, otherwise say N. Note that
> + to use a serial port as a console, this must be included in kernel and
> + not as a module.
> +
> +config SERIAL_PIC32_CONSOLE
> + bool "PIC32 serial console support"
> + depends on SERIAL_PIC32
> + select SERIAL_CORE_CONSOLE
> + help
> + If you have a PIC32, this driver supports the putting a console on one
> + of the serial ports.
> +
> + Say Y to use the PIC32 console, otherwise say N.
> +
> config SERIAL_MPC52xx
> tristate "Freescale MPC52xx/MPC512x family PSC serial support"
> depends on PPC_MPC52xx || PPC_MPC512x
> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> index 5ab4111..bc5e354 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -93,6 +93,7 @@ obj-$(CONFIG_SERIAL_CONEXANT_DIGICOLOR) += digicolor-usart.o
> obj-$(CONFIG_SERIAL_MEN_Z135) += men_z135_uart.o
> obj-$(CONFIG_SERIAL_SPRD) += sprd_serial.o
> obj-$(CONFIG_SERIAL_STM32) += stm32-usart.o
> +obj-$(CONFIG_SERIAL_PIC32) += pic32_uart.o
>
> # GPIOLIB helpers for modem control lines
> obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o
> diff --git a/drivers/tty/serial/pic32_uart.c b/drivers/tty/serial/pic32_uart.c
> new file mode 100644
> index 0000000..5c05c11
> --- /dev/null
> +++ b/drivers/tty/serial/pic32_uart.c
> @@ -0,0 +1,927 @@
> +/*
> + * PIC32 Integrated Serial Driver.
> + *
> + * Copyright (C) 2015 Microchip Technology, Inc.
> + *
> + * Authors:
> + * Steve Scott <steve.scott@xxxxxxxxxxxxx>,
> + * Sorin-Andrei Pistirica <andrei.pistirica@xxxxxxxxxxxxx>
> + *
> + * Licensed under GPLv2 or later.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_gpio.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/console.h>
> +#include <linux/clk-provider.h>

Didn't notice clock provider here.

> +#include <linux/clk.h>
> +#include <linux/clkdev.h>
> +#include <linux/tty.h>
> +#include <linux/tty_flip.h>
> +#include <linux/sysrq.h>
> +#include <linux/serial.h>
> +#include <linux/serial_core.h>
> +#include <uapi/linux/serial_core.h>
> +#include <linux/delay.h>

Revisit this list and leave exactly what is used.

> +
> +#include "pic32_uart.h"
> +
> +/* UART name and device definitions */
> +#define PIC32_DEV_NAME "pic32-uart"
> +#define PIC32_MAX_UARTS 6
> +
> +#define PIC32_SDEV_NAME "ttyS"
> +#define PIC32_SDEV_MAJOR TTY_MAJOR
> +#define PIC32_SDEV_MINOR 64
> +
> +/* pic32_sport pointer for console use */
> +static struct pic32_sport *pic32_sports[PIC32_MAX_UARTS];
> +
> +static inline int pic32_enable_clock(struct pic32_sport *sport)
> +{
> + sport->ref_clk++;
> +

Useless empty line (do in one style).

> + return clk_prepare_enable(sport->clk);
> +}
> +
> +static inline void pic32_disable_clock(struct pic32_sport *sport)
> +{
> + sport->ref_clk--;
> + clk_disable_unprepare(sport->clk);
> +}
> +
> +/* serial core request to check if uart tx buffer is empty */
> +static unsigned int pic32_uart_tx_empty(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> + u32 val = pic32_uart_read(sport, PIC32_UART_STA);
> +
> + return (val & PIC32_UART_STA_TRMT) ? 1 : 0;
> +}
> +
> +/* serial core request to set UART outputs */
> +static void pic32_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> +
> + /* set loopback mode */
> + if (mctrl & TIOCM_LOOP)
> + pic32_uart_rset(PIC32_UART_MODE_LPBK, sport, PIC32_UART_MODE);
> + else
> + pic32_uart_rclr(PIC32_UART_MODE_LPBK, sport, PIC32_UART_MODE);
> +}
> +
> +/* get the state of CTS input pin for this port */
> +static unsigned int get_cts_state(struct pic32_sport *sport)
> +{
> + /* default state must be asserted */
> + int val = 1;

Redundant.

> +
> + /* read and invert UxCTS */
> + if (gpio_is_valid(sport->cts_gpio))
> + val = !gpio_get_value(sport->cts_gpio);

If (â)
return â;

return 1;

> +
> + return val;
> +}
> +
> +/* serial core request to return the state of misc UART input pins */
> +static unsigned int pic32_uart_get_mctrl(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> + unsigned int mctrl = 0;
> +
> + if (!sport->hw_flow_ctrl) {
> + mctrl |= TIOCM_CTS;

> + goto ret;
> + }
> +
> + if (get_cts_state(sport))

else if (get_cts_state(sport))

> + mctrl |= TIOCM_CTS;
> +

> +ret:

And remove useless label, besides that fact that its name is awfully chosen.

> + /* DSR and CD are not supported in PIC32, so return 1
> + * RI is not supported in PIC32, so return 0
> + */
> + mctrl |= TIOCM_CD;
> + mctrl |= TIOCM_DSR;
> +
> + return mctrl;
> +}
> +
> +/* stop tx and start tx are not called in pairs, therefore a flag indicates
> + * the status of irq to control the irq-depth.
> + */
> +static inline void pic32_uart_irqtxen(struct pic32_sport *sport, u8 en)
> +{
> + if (en && !tx_irq_enabled(sport)) {
> + enable_irq(sport->irq_tx);
> + tx_irq_enabled(sport) = 1;
> + } else if (!en && tx_irq_enabled(sport)) {
> + /* use disable_irq_nosync() and not disable_irq() to avoid self
> + * imposed deadlock by not waiting for irq handler to end,
> + * since this callback is called from interrupt context.
> + */
> + disable_irq_nosync(sport->irq_tx);
> + tx_irq_enabled(sport) = 0;
> + }
> +}
> +
> +/* serial core request to disable tx ASAP (used for flow control) */
> +static void pic32_uart_stop_tx(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> +
> + if (!(pic32_uart_read(sport, PIC32_UART_MODE) & PIC32_UART_MODE_ON))
> + return;
> +
> + if (!(pic32_uart_read(sport, PIC32_UART_STA) & PIC32_UART_STA_UTXEN))
> + return;
> +
> + /* wait for tx empty */
> + while (!(pic32_uart_read(sport, PIC32_UART_STA) & PIC32_UART_STA_TRMT))
> + udelay(1);
> +
> + pic32_uart_rclr(PIC32_UART_STA_UTXEN, sport, PIC32_UART_STA);
> + pic32_uart_irqtxen(sport, 0);
> +}
> +
> +/* serial core request to (re)enable tx */
> +static void pic32_uart_start_tx(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> +
> + pic32_uart_irqtxen(sport, 1);
> + pic32_uart_rset(PIC32_UART_STA_UTXEN, sport, PIC32_UART_STA);
> +}
> +
> +/* serial core request to stop rx, called before port shutdown */
> +static void pic32_uart_stop_rx(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> +
> + /* disable rx interrupts */
> + disable_irq(sport->irq_rx);
> +
> + /* receiver Enable bit OFF */
> + pic32_uart_rclr(PIC32_UART_STA_URXEN, sport, PIC32_UART_STA);
> +}
> +
> +/* serial core request to start/stop emitting break char */
> +static void pic32_uart_break_ctl(struct uart_port *port, int ctl)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> + unsigned long flags = 0;

Useless assignment.

> +
> + spin_lock_irqsave(&port->lock, flags);
> +
> + if (ctl)
> + pic32_uart_rset(PIC32_UART_STA_UTXBRK, sport, PIC32_UART_STA);
> + else
> + pic32_uart_rclr(PIC32_UART_STA_UTXBRK, sport, PIC32_UART_STA);
> +
> + spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +/* get port type in string format */
> +static const char *pic32_uart_type(struct uart_port *port)
> +{
> + return (port->type == PORT_PIC32) ? PIC32_DEV_NAME : NULL;
> +}
> +
> +/* read all chars in rx fifo and send them to core */
> +static void pic32_uart_do_rx(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> + struct tty_port *tty;
> + unsigned int max_count;
> +
> + /* limit number of char read in interrupt, should not be
> + * higher than fifo size anyway since we're much faster than
> + * serial port
> + */
> + max_count = PIC32_UART_RX_FIFO_DEPTH;
> +
> + spin_lock(&port->lock);
> +
> + tty = &port->state->port;
> +
> + do {
> + u32 sta_reg, c;
> + char flag;
> +
> + /* get overrun/fifo empty information from status register */
> + sta_reg = pic32_uart_read(sport, PIC32_UART_STA);
> + if (unlikely(sta_reg & PIC32_UART_STA_OERR)) {
> +
> + /* fifo reset is required to clear interrupt */
> + pic32_uart_rclr(PIC32_UART_STA_OERR, sport,
> + PIC32_UART_STA);
> +
> + port->icount.overrun++;
> + tty_insert_flip_char(tty, 0, TTY_OVERRUN);
> + }
> +
> + /* Can at least one more character can be read? */
> + if (!(sta_reg & PIC32_UART_STA_URXDA))
> + break;
> +
> + /* read the character and increment the rx counter */
> + c = pic32_uart_read(sport, PIC32_UART_RX);
> +
> + port->icount.rx++;
> + flag = TTY_NORMAL;
> + c &= 0xff;
> +
> + if (unlikely((sta_reg & PIC32_UART_STA_PERR) ||
> + (sta_reg & PIC32_UART_STA_FERR))) {
> +
> + /* do stats first */
> + if (sta_reg & PIC32_UART_STA_PERR)
> + port->icount.parity++;
> + if (sta_reg & PIC32_UART_STA_FERR)
> + port->icount.frame++;
> +
> + /* update flag wrt read_status_mask */
> + sta_reg &= port->read_status_mask;
> +
> + if (sta_reg & PIC32_UART_STA_FERR)
> + flag = TTY_FRAME;
> + if (sta_reg & PIC32_UART_STA_PERR)
> + flag = TTY_PARITY;
> + }
> +
> + if (uart_handle_sysrq_char(port, c))
> + continue;
> +
> + if ((sta_reg & port->ignore_status_mask) == 0)
> + tty_insert_flip_char(tty, c, flag);
> +
> + } while (--max_count);
> +
> + spin_unlock(&port->lock);
> +
> + tty_flip_buffer_push(tty);
> +}
> +
> +/* fill tx fifo with chars to send, stop when fifo is about to be full
> + * or when all chars have been sent.
> + */
> +static void pic32_uart_do_tx(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> + struct circ_buf *xmit = &port->state->xmit;
> + unsigned int max_count = PIC32_UART_TX_FIFO_DEPTH;
> +
> + if (port->x_char) {
> + pic32_uart_write(port->x_char, sport, PIC32_UART_TX);
> + port->icount.tx++;
> + port->x_char = 0;
> + return;
> + }
> +
> + if (uart_tx_stopped(port)) {
> + pic32_uart_stop_tx(port);
> + return;
> + }
> +
> + if (uart_circ_empty(xmit))
> + goto txq_empty;
> +
> + /* keep stuffing chars into uart tx buffer
> + * 1) until uart fifo is full
> + * or
> + * 2) until the circ buffer is empty
> + * (all chars have been sent)
> + * or
> + * 3) until the max count is reached
> + * (prevents lingering here for too long in certain cases)
> + */
> + while (!(PIC32_UART_STA_UTXBF &
> + pic32_uart_rval(sport, PIC32_UART_STA))) {
> + unsigned int c = xmit->buf[xmit->tail];
> +
> + pic32_uart_write(c, sport, PIC32_UART_TX);
> +
> + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
> + port->icount.tx++;
> + --max_count;

It's not used outside of while, so â

> + if (uart_circ_empty(xmit))
> + break;
> + if (max_count == 0)

if (--mac_count == 0)

> + break;

Or you can move the original 'if' condition inside 'while' one since
it's a last in the loop.

> + }
> +
> + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> + uart_write_wakeup(port);
> +
> + if (uart_circ_empty(xmit))
> + goto txq_empty;
> +
> + return;
> +
> +txq_empty:
> + pic32_uart_irqtxen(sport, 0);
> +}
> +
> +/* RX interrupt handler */
> +static irqreturn_t pic32_uart_rx_interrupt(int irq, void *dev_id)
> +{
> + struct uart_port *port = dev_id;
> +
> + pic32_uart_do_rx(port);
> +
> + return IRQ_HANDLED;
> +}
> +
> +/* TX interrupt handler */
> +static irqreturn_t pic32_uart_tx_interrupt(int irq, void *dev_id)
> +{
> + struct uart_port *port = dev_id;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&port->lock, flags);
> + pic32_uart_do_tx(port);
> + spin_unlock_irqrestore(&port->lock, flags);
> +
> + return IRQ_HANDLED;
> +}
> +
> +/* FAULT interrupt handler */
> +static irqreturn_t pic32_uart_fault_interrupt(int irq, void *dev_id)
> +{
> + /* do nothing: pic32_uart_do_rx() handles faults. */
> + return IRQ_HANDLED;
> +}
> +
> +/* enable rx & tx operation on uart */
> +static void pic32_uart_en_and_unmask(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> +
> + pic32_uart_rset(PIC32_UART_STA_UTXEN | PIC32_UART_STA_URXEN,
> + sport, PIC32_UART_STA);
> + pic32_uart_rset(PIC32_UART_MODE_ON, sport, PIC32_UART_MODE);
> +}
> +
> +/* disable rx & tx operation on uart */
> +static void pic32_uart_dsbl_and_mask(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> +
> + pic32_uart_rclr(PIC32_UART_MODE_ON, sport, PIC32_UART_MODE);
> + pic32_uart_rclr(PIC32_UART_STA_UTXEN | PIC32_UART_STA_URXEN,
> + sport, PIC32_UART_STA);
> +}
> +
> +/* serial core request to initialize uart and start rx operation */
> +static int pic32_uart_startup(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> + u32 dflt_baud = ((port->uartclk / PIC32_UART_DFLT_BRATE) / 16) - 1;

Useless external parens.

> + unsigned long flags;
> + int ret = 0;

Useless assignment.

> +
> + local_irq_save(flags);
> +
> + ret = pic32_enable_clock(sport);
> + if (ret)
> + goto out_unlock;
> +
> + /* clear status and mode registers */
> + pic32_uart_write(0, sport, PIC32_UART_MODE);
> + pic32_uart_write(0, sport, PIC32_UART_STA);
> +
> + /* disable uart and mask all interrupts */
> + pic32_uart_dsbl_and_mask(port);
> +
> + /* set default baud */
> + pic32_uart_write(dflt_baud, sport, PIC32_UART_BRG);
> +
> + local_irq_restore(flags);
> +
> + /* Each UART of a PIC32 has three interrupts therefore,
> + * we setup driver to register the 3 irqs for the device.
> + *
> + * For each irq request_irq() is called with interrupt disabled.
> + * And the irq is enabled as soon as we are ready to handle them.
> + */
> + tx_irq_enabled(sport) = 0;
> +
> + sport->irq_fault_name = kasprintf(GFP_KERNEL, "%s%d-fault",
> + pic32_uart_type(port),
> + sport->idx);
> + irq_set_status_flags(sport->irq_fault, IRQ_NOAUTOEN);
> + ret = request_irq(sport->irq_fault, pic32_uart_fault_interrupt,
> + sport->irqflags_fault, sport->irq_fault_name, port);
> + if (ret) {
> + dev_err(port->dev, "%s: request irq(%d) err! ret:%d name:%s\n",
> + __func__, sport->irq_fault, ret,
> + pic32_uart_type(port));
> + goto out_done;
> + }
> +
> + sport->irq_rx_name = kasprintf(GFP_KERNEL, "%s%d-rx",
> + pic32_uart_type(port),
> + sport->idx);
> + irq_set_status_flags(sport->irq_rx, IRQ_NOAUTOEN);
> + ret = request_irq(sport->irq_rx, pic32_uart_rx_interrupt,
> + sport->irqflags_rx, sport->irq_rx_name, port);
> + if (ret) {
> + dev_err(port->dev, "%s: request irq(%d) err! ret:%d name:%s\n",
> + __func__, sport->irq_rx, ret,
> + pic32_uart_type(port));
> + goto out_done;
> + }
> +
> + sport->irq_tx_name = kasprintf(GFP_KERNEL, "%s%d-tx",
> + pic32_uart_type(port),
> + sport->idx);
> + irq_set_status_flags(sport->irq_tx, IRQ_NOAUTOEN);
> + ret = request_irq(sport->irq_tx, pic32_uart_tx_interrupt,
> + sport->irqflags_tx, sport->irq_tx_name, port);
> + if (ret) {
> + dev_err(port->dev, "%s: request irq(%d) err! ret:%d name:%s\n",
> + __func__, sport->irq_tx, ret,
> + pic32_uart_type(port));
> + goto out_done;
> + }
> +
> + local_irq_save(flags);
> +
> + /* set rx interrupt on first receive */
> + pic32_uart_rclr(PIC32_UART_STA_URXISEL1 | PIC32_UART_STA_URXISEL0,
> + sport, PIC32_UART_STA);
> +
> + /* set interrupt on empty */
> + pic32_uart_rclr(PIC32_UART_STA_UTXISEL1, sport, PIC32_UART_STA);
> +
> + /* enable all interrupts and eanable uart */
> + pic32_uart_en_and_unmask(port);
> +
> + enable_irq(sport->irq_fault);
> + enable_irq(sport->irq_rx);
> +
> +out_unlock:
> + local_irq_restore(flags);
> +
> +out_done:
> + return ret;
> +}
> +
> +/* serial core request to flush & disable uart */
> +static void pic32_uart_shutdown(struct uart_port *port)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> + unsigned long flags;
> +
> + /* disable uart */
> + spin_lock_irqsave(&port->lock, flags);
> + pic32_uart_dsbl_and_mask(port);
> + spin_unlock_irqrestore(&port->lock, flags);
> + pic32_disable_clock(sport);
> +
> + /* free all 3 interrupts for this UART */
> + free_irq(sport->irq_fault, port);
> + free_irq(sport->irq_tx, port);
> + free_irq(sport->irq_rx, port);
> +}
> +
> +/* serial core request to change current uart setting */
> +static void pic32_uart_set_termios(struct uart_port *port,
> + struct ktermios *new,
> + struct ktermios *old)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> + unsigned int baud;
> + unsigned int quot;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&port->lock, flags);
> +
> + /* disable uart and mask all interrupts while changing speed */
> + pic32_uart_dsbl_and_mask(port);
> +
> + /* stop bit options */
> + if (new->c_cflag & CSTOPB)
> + pic32_uart_rset(PIC32_UART_MODE_STSEL, sport, PIC32_UART_MODE);
> + else
> + pic32_uart_rclr(PIC32_UART_MODE_STSEL, sport, PIC32_UART_MODE);
> +
> + /* parity options */
> + if (new->c_cflag & PARENB) {
> + if (new->c_cflag & PARODD) {
> + pic32_uart_rset(PIC32_UART_MODE_PDSEL1, sport,
> + PIC32_UART_MODE);
> + pic32_uart_rclr(PIC32_UART_MODE_PDSEL0, sport,
> + PIC32_UART_MODE);
> + } else {
> + pic32_uart_rset(PIC32_UART_MODE_PDSEL0, sport,
> + PIC32_UART_MODE);
> + pic32_uart_rclr(PIC32_UART_MODE_PDSEL1, sport,
> + PIC32_UART_MODE);
> + }
> + } else {
> + pic32_uart_rclr(PIC32_UART_MODE_PDSEL1 | PIC32_UART_MODE_PDSEL0,
> + sport, PIC32_UART_MODE);
> + }
> + /* if hw flow ctrl, then the pins must be specified in device tree */
> + if ((new->c_cflag & CRTSCTS) && sport->hw_flow_ctrl) {
> + /* enable hardware flow control */
> + pic32_uart_rset(PIC32_UART_MODE_UEN1, sport, PIC32_UART_MODE);
> + pic32_uart_rclr(PIC32_UART_MODE_UEN0, sport, PIC32_UART_MODE);
> + pic32_uart_rclr(PIC32_UART_MODE_RTSMD, sport, PIC32_UART_MODE);
> + } else {
> + /* disable hardware flow control */
> + pic32_uart_rclr(PIC32_UART_MODE_UEN1, sport, PIC32_UART_MODE);
> + pic32_uart_rclr(PIC32_UART_MODE_UEN0, sport, PIC32_UART_MODE);
> + pic32_uart_rclr(PIC32_UART_MODE_RTSMD, sport, PIC32_UART_MODE);
> + }
> +
> + /* update baud */
> + baud = uart_get_baud_rate(port, new, old, 0, port->uartclk / 16);
> + quot = uart_get_divisor(port, baud) - 1;
> + pic32_uart_write(quot, sport, PIC32_UART_BRG);
> + uart_update_timeout(port, new->c_cflag, baud);
> +
> + /* enable uart */
> + pic32_uart_en_and_unmask(port);
> +
> + spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +/* serial core request to claim uart iomem */
> +static int pic32_uart_request_port(struct uart_port *port)
> +{
> + struct platform_device *pdev = to_platform_device(port->dev);
> + struct resource *res_mem;
> + unsigned int res_size;
> +
> + res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (unlikely(!res_mem))
> + return -EINVAL;
> + res_size = resource_size(res_mem);
> +
> + if (!request_mem_region(port->mapbase, res_size, "pic32_uart_mem")) {
> + dev_err(port->dev, "Memory region busy\n");

Looks a bit useless, return code will be converted to Resource is busy
in userspace.

> + return -EBUSY;
> + }
> +
> + port->membase = devm_ioremap_nocache(port->dev,
> + port->mapbase, res_size);

> + if (!port->membase) {
> + dev_err(port->dev, "Unable to map registers\n");
> + release_mem_region(port->mapbase, res_size);
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +/* serial core request to release uart iomem */
> +static void pic32_uart_release_port(struct uart_port *port)
> +{
> + struct platform_device *pdev = to_platform_device(port->dev);
> + struct resource *res_mem;
> + unsigned int res_size;
> +
> + res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (unlikely(!res_mem))
> + return;
> + res_size = resource_size(res_mem);
> +
> + release_mem_region(port->mapbase, res_size);
> + devm_iounmap(port->dev, port->membase);

And why do you need to do this explicitly?

> +}
> +
> +/* serial core request to do any port required auto-configuration */
> +static void pic32_uart_config_port(struct uart_port *port, int flags)
> +{
> + if (flags & UART_CONFIG_TYPE) {
> + if (pic32_uart_request_port(port))
> + return;
> + port->type = PORT_PIC32;
> + }
> +}
> +
> +/* serial core request to check that port information in serinfo are suitable */
> +static int pic32_uart_verify_port(struct uart_port *port,
> + struct serial_struct *serinfo)
> +{
> + if (port->type != PORT_PIC32)
> + return -EINVAL;
> + if (port->irq != serinfo->irq)
> + return -EINVAL;
> + if (port->iotype != serinfo->io_type)
> + return -EINVAL;
> + if (port->mapbase != (unsigned long)serinfo->iomem_base)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +/* serial core callbacks */
> +static const struct uart_ops pic32_uart_ops = {
> + .tx_empty = pic32_uart_tx_empty,
> + .get_mctrl = pic32_uart_get_mctrl,
> + .set_mctrl = pic32_uart_set_mctrl,
> + .start_tx = pic32_uart_start_tx,
> + .stop_tx = pic32_uart_stop_tx,
> + .stop_rx = pic32_uart_stop_rx,
> + .break_ctl = pic32_uart_break_ctl,
> + .startup = pic32_uart_startup,
> + .shutdown = pic32_uart_shutdown,
> + .set_termios = pic32_uart_set_termios,
> + .type = pic32_uart_type,
> + .release_port = pic32_uart_release_port,
> + .request_port = pic32_uart_request_port,
> + .config_port = pic32_uart_config_port,
> + .verify_port = pic32_uart_verify_port,
> +};
> +
> +#ifdef CONFIG_SERIAL_PIC32_CONSOLE
> +/* output given char */
> +static void pic32_console_putchar(struct uart_port *port, int ch)
> +{
> + struct pic32_sport *sport = to_pic32_sport(port);
> +
> + if (!(pic32_uart_read(sport, PIC32_UART_MODE) & PIC32_UART_MODE_ON))
> + return;
> +
> + if (!(pic32_uart_read(sport, PIC32_UART_STA) & PIC32_UART_STA_UTXEN))
> + return;
> +
> + /* wait for tx empty */
> + while (!(pic32_uart_read(sport, PIC32_UART_STA) & PIC32_UART_STA_TRMT))
> + udelay(1);
> +
> + pic32_uart_write(ch & 0xff, sport, PIC32_UART_TX);
> +}
> +
> +/* console core request to output given string */
> +static void pic32_console_write(struct console *co, const char *s,
> + unsigned int count)
> +{
> + struct pic32_sport *sport = pic32_sports[co->index];
> + struct uart_port *port = pic32_get_port(sport);
> +
> + /* call uart helper to deal with \r\n */
> + uart_console_write(port, s, count, pic32_console_putchar);
> +}
> +
> +/* console core request to setup given console, find matching uart
> + * port and setup it.
> + */
> +static int pic32_console_setup(struct console *co, char *options)
> +{
> + struct pic32_sport *sport;
> + struct uart_port *port = NULL;
> + int baud = 115200;
> + int bits = 8;
> + int parity = 'n';
> + int flow = 'n';
> + int ret = 0;
> +
> + if (unlikely(co->index < 0 || co->index >= PIC32_MAX_UARTS))
> + return -ENODEV;
> +
> + sport = pic32_sports[co->index];
> + if (!sport)
> + return -ENODEV;
> + port = pic32_get_port(sport);
> +
> + ret = pic32_enable_clock(sport);
> + if (ret)
> + return ret;
> +
> + if (options)
> + uart_parse_options(options, &baud, &parity, &bits, &flow);
> +
> + return uart_set_options(port, co, baud, parity, bits, flow);
> +}
> +
> +static struct uart_driver pic32_uart_driver;
> +static struct console pic32_console = {
> + .name = PIC32_SDEV_NAME,
> + .write = pic32_console_write,
> + .device = uart_console_device,
> + .setup = pic32_console_setup,
> + .flags = CON_PRINTBUFFER,
> + .index = -1,
> + .data = &pic32_uart_driver,
> +};
> +#define PIC32_SCONSOLE (&pic32_console)
> +
> +static int __init pic32_console_init(void)
> +{
> + register_console(&pic32_console);
> + return 0;
> +}
> +console_initcall(pic32_console_init);
> +
> +static inline bool is_pic32_console_port(struct uart_port *port)
> +{
> + return (port->cons && port->cons->index == port->line);

Useless parens.

> +}
> +
> +/*
> + * Late console initialization.
> + */
> +static int __init pic32_late_console_init(void)
> +{
> + if (!(pic32_console.flags & CON_ENABLED))
> + register_console(&pic32_console);
> +
> + return 0;
> +}
> +
> +core_initcall(pic32_late_console_init);
> +
> +#else
> +#define PIC32_SCONSOLE NULL
> +#endif
> +
> +static struct uart_driver pic32_uart_driver = {
> + .owner = THIS_MODULE,
> + .driver_name = PIC32_DEV_NAME,
> + .dev_name = PIC32_SDEV_NAME,
> + .major = PIC32_SDEV_MAJOR,
> + .minor = PIC32_SDEV_MINOR,
> + .nr = PIC32_MAX_UARTS,
> + .cons = PIC32_SCONSOLE,
> +};
> +
> +static int pic32_uart_probe(struct platform_device *pdev)
> +{
> + struct device_node *np = pdev->dev.of_node;
> + struct pic32_sport *sport;
> + int uart_idx = 0;
> + struct resource *res_mem;
> + struct uart_port *port;

> + int ret = 0;

Unneeded assignment.

> +
> + uart_idx = of_alias_get_id(np, "serial");
> + if (uart_idx < 0 || uart_idx >= PIC32_MAX_UARTS)
> + return -EINVAL;
> +
> + res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res_mem)
> + return -EINVAL;
> +
> + sport = devm_kzalloc(&pdev->dev, sizeof(*sport), GFP_KERNEL);
> + if (!sport)
> + return -ENOMEM;
> +
> + sport->idx = uart_idx;
> + sport->irq_fault = irq_of_parse_and_map(np, 0);
> + sport->irqflags_fault = IRQF_NO_THREAD;
> + sport->irq_rx = irq_of_parse_and_map(np, 1);
> + sport->irqflags_rx = IRQF_NO_THREAD;
> + sport->irq_tx = irq_of_parse_and_map(np, 2);
> + sport->irqflags_tx = IRQF_NO_THREAD;
> + sport->clk = devm_clk_get(&pdev->dev, NULL);
> + sport->cts_gpio = -EINVAL;
> + sport->dev = &pdev->dev;
> +
> + ret = pic32_enable_clock(sport);
> + if (ret) {
> + dev_err(&pdev->dev, "clk enable ?\n");
> + goto err;
> + }
> +
> + /* Hardware flow control: gpios
> + * !Note: Basically, CTS is needed for reading the status.
> + */
> + sport->hw_flow_ctrl = false;
> + sport->cts_gpio = of_get_named_gpio(np, "cts-gpios", 0);
> + if (gpio_is_valid(sport->cts_gpio)) {
> + sport->hw_flow_ctrl = true;
> +
> + ret = devm_gpio_request(sport->dev,
> + sport->cts_gpio, "CTS");
> + if (ret) {
> + dev_err(&pdev->dev,
> + "error requesting CTS GPIO\n");
> + goto err_disable_clk;
> + }
> +
> + ret = gpio_direction_input(sport->cts_gpio);
> + if (ret) {
> + dev_err(&pdev->dev, "error setting CTS GPIO\n");
> + goto err_disable_clk;
> + }
> + }
> +
> + pic32_sports[uart_idx] = sport;
> + port = &sport->port;
> + memset(port, 0, sizeof(*port));
> + port->iotype = UPIO_MEM;
> + port->mapbase = res_mem->start;
> + port->ops = &pic32_uart_ops;
> + port->flags = UPF_BOOT_AUTOCONF;
> + port->dev = &pdev->dev;
> + port->fifosize = PIC32_UART_TX_FIFO_DEPTH;
> + port->uartclk = clk_get_rate(sport->clk);
> + port->line = uart_idx;
> +
> + ret = uart_add_one_port(&pic32_uart_driver, port);
> + if (ret) {
> + port->membase = NULL;
> + dev_err(port->dev, "%s: uart add port error!\n", __func__);
> + goto err_disable_clk;
> + }
> +
> +#ifdef CONFIG_SERIAL_PIC32_CONSOLE
> + if (is_pic32_console_port(port) &&
> + (pic32_console.flags & CON_ENABLED)) {
> + /* The peripheral clock has been enabled by console_setup,
> + * so disable it till the port is used.
> + */
> + pic32_disable_clock(sport);

(1)

> + }
> +#endif
> +
> + platform_set_drvdata(pdev, port);
> +
> + dev_info(&pdev->dev, "%s: uart(%d) driver initialized.\n",
> + __func__, uart_idx);
> + ret = 0;
> +

(2)

> +err_disable_clk:
> + /* disable clock till the port is used. */
> + pic32_disable_clock(sport);

(3) double disable clock call?

> +err:
> + /* automatic unroll of sport and gpios */
> + return ret;
> +}
> +
> +static int pic32_uart_remove(struct platform_device *pdev)
> +{
> + struct uart_port *port = platform_get_drvdata(pdev);
> + struct pic32_sport *sport = to_pic32_sport(port);
> +
> + uart_remove_one_port(&pic32_uart_driver, port);
> + pic32_disable_clock(sport);
> + platform_set_drvdata(pdev, NULL);
> + pic32_sports[sport->idx] = NULL;
> +
> + /* automatic unroll of sport and gpios */
> + return 0;
> +}
> +
> +static const struct of_device_id pic32_serial_dt_ids[] = {
> + { .compatible = "microchip,pic32mzda-uart" },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, pic32_serial_dt_ids);
> +
> +static struct platform_driver pic32_uart_platform_driver = {
> + .probe = pic32_uart_probe,
> + .remove = pic32_uart_remove,
> + .driver = {
> + .name = PIC32_DEV_NAME,

> + .owner = THIS_MODULE,

Shouldn't core set this?

> + .of_match_table = of_match_ptr(pic32_serial_dt_ids),
> + },
> +};
> +
> +static int __init pic32_uart_init(void)
> +{
> + int ret;
> +
> + ret = uart_register_driver(&pic32_uart_driver);
> + if (ret) {
> + pr_err("failed to register %s:%d\n",
> + pic32_uart_driver.driver_name, ret);
> + return ret;
> + }
> +
> + ret = platform_driver_register(&pic32_uart_platform_driver);
> + if (ret) {
> + pr_err("fail to register pic32 uart\n");
> + uart_unregister_driver(&pic32_uart_driver);
> + }
> +
> + return ret;
> +}
> +arch_initcall(pic32_uart_init);
> +
> +static void __exit pic32_uart_exit(void)
> +{
> +#ifdef CONFIG_SERIAL_PIC32_CONSOLE
> + unregister_console(&pic32_console);
> +#endif
> + platform_driver_unregister(&pic32_uart_platform_driver);
> + uart_unregister_driver(&pic32_uart_driver);
> +}
> +module_exit(pic32_uart_exit);
> +
> +MODULE_AUTHOR("Steve Scott <steve.scott@xxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Microchip PIC32 integrated serial port driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/tty/serial/pic32_uart.h b/drivers/tty/serial/pic32_uart.h
> new file mode 100644
> index 0000000..b2f6960
> --- /dev/null
> +++ b/drivers/tty/serial/pic32_uart.h
> @@ -0,0 +1,198 @@
> +/*
> + * PIC32 Integrated Serial Driver.
> + *
> + * Copyright (C) 2015 Microchip Technology, Inc.
> + *
> + * Authors:
> + * Sorin-Andrei Pistirica <andrei.pistirica@xxxxxxxxxxxxx>
> + *
> + * Licensed under GPLv2 or later.
> + */
> +#ifndef __DT_PIC32_UART_H__
> +#define __DT_PIC32_UART_H__
> +
> +#define PIC32_UART_DFLT_BRATE (9600)
> +#define PIC32_UART_TX_FIFO_DEPTH (8)
> +#define PIC32_UART_RX_FIFO_DEPTH (8)
> +
> +struct pic32_console_opt {
> + int baud;
> + int parity;
> + int bits;
> + int flow;
> +};

+ empty line

> +/* struct pic32_sport - pic32 serial port descriptor

/**

> + * @port: uart port descriptor
> + * @idx: port index
> + * @irq_fault: virtual fault interrupt number
> + * @irqflags_fault: flags related to fault irq
> + * @irq_fault_name: irq fault name
> + * @irq_rx: virtual rx interrupt number
> + * @irqflags_rx: flags related to rx irq
> + * @irq_rx_name: irq rx name
> + * @irq_tx: virtual tx interrupt number
> + * @irqflags_tx: : flags related to tx irq
> + * @irq_tx_name: irq tx name
> + * @cts_gpio: clear to send gpio
> + * @dev: device descriptor
> + **/
> +struct pic32_sport {
> + struct uart_port port;
> + struct pic32_console_opt opt;
> + int idx;
> +
> + int irq_fault;
> + int irqflags_fault;
> + const char *irq_fault_name;
> + int irq_rx;
> + int irqflags_rx;
> + const char *irq_rx_name;
> + int irq_tx;
> + int irqflags_tx;
> + const char *irq_tx_name;
> + u8 enable_tx_irq;
> +
> + bool hw_flow_ctrl;
> + int cts_gpio;
> +
> + int ref_clk;
> + struct clk *clk;
> +
> + struct device *dev;
> +};
> +#define to_pic32_sport(c) container_of(c, struct pic32_sport, port)
> +#define pic32_get_port(sport) (&sport->port)
> +#define pic32_get_opt(sport) (&sport->opt)
> +#define tx_irq_enabled(sport) (sport->enable_tx_irq)
> +
> +struct pic32_reg {
> + u32 val;
> + u32 clr;
> + u32 set;
> + u32 inv;
> +} __packed;
> +#define PIC32_REGS 4
> +#define PIC32_REG_SIZE 4
> +
> +enum pic32_uart_regs {
> + PIC32_UART_UNKNOWN = 0,
> + PIC32_UART_MODE = 1,
> + PIC32_UART_STA = 2,
> + PIC32_UART_TX = 3,
> + PIC32_UART_RX = 4,
> + PIC32_UART_BRG = 5,
> +
> + /* add above this line */
> + PIC32_UART_LAST
> +};
> +
> +/* uart register offsets */
> +static u32 pic32_uart_lookup_reg[PIC32_UART_LAST] = {
> + [PIC32_UART_MODE] = 0 * PIC32_REGS * PIC32_REG_SIZE,
> + [PIC32_UART_STA] = 1 * PIC32_REGS * PIC32_REG_SIZE,
> + [PIC32_UART_TX] = 2 * PIC32_REGS * PIC32_REG_SIZE,
> + [PIC32_UART_RX] = 3 * PIC32_REGS * PIC32_REG_SIZE,
> + [PIC32_UART_BRG] = 4 * PIC32_REGS * PIC32_REG_SIZE,
> +};
> +
> +static inline void __iomem *pic32_uart_get_reg(struct pic32_sport *sport,
> + enum pic32_uart_regs reg)
> +{
> + struct uart_port *port = pic32_get_port(sport);
> +
> + return port->membase + pic32_uart_lookup_reg[reg];
> +}
> +
> +static inline u32 pic32_uart_rval(struct pic32_sport *sport,
> + enum pic32_uart_regs reg)
> +{
> + void __iomem *addr = pic32_uart_get_reg(sport, reg);
> + struct pic32_reg __iomem *reg_addr = (struct pic32_reg __iomem *)addr;
> +
> + return readl(&reg_addr->val);
> +}
> +
> +static inline void pic32_uart_rset(u32 val,
> + struct pic32_sport *sport,
> + enum pic32_uart_regs reg)

Better to use more logical way for this, i.e.
(sport, regs, value)

Same for below.

> +{
> + void __iomem *addr = pic32_uart_get_reg(sport, reg);
> + struct pic32_reg __iomem *reg_addr = (struct pic32_reg __iomem *)addr;

struct pic32_reg __iomem *reg = pic32_uart_get_reg(sport, regs);
writel(value, &reg->set);

looks much better, does it?

> +
> + writel(val, &reg_addr->set);
> +}
> +
> +static inline void pic32_uart_rclr(u32 val,
> + struct pic32_sport *sport,
> + enum pic32_uart_regs reg)
> +{
> + void __iomem *addr = pic32_uart_get_reg(sport, reg);
> + struct pic32_reg __iomem *reg_addr = (struct pic32_reg __iomem *)addr;
> +
> + writel(val, &reg_addr->clr);
> +}
> +
> +static inline void pic32_uart_rinv(u32 val,
> + struct pic32_sport *sport,
> + enum pic32_uart_regs reg)
> +{
> + void __iomem *addr = pic32_uart_get_reg(sport, reg);
> + struct pic32_reg __iomem *reg_addr = (struct pic32_reg __iomem *)addr;
> +
> + writel(val, &reg_addr->inv);
> +}
> +
> +static inline void pic32_uart_write(u32 val,
> + struct pic32_sport *sport,
> + enum pic32_uart_regs reg)
> +{
> + void __iomem *addr = pic32_uart_get_reg(sport, reg);
> +
> + writel(val, addr);
> +}
> +
> +static inline u32 pic32_uart_read(struct pic32_sport *sport,
> + enum pic32_uart_regs reg)
> +{
> + void __iomem *addr = pic32_uart_get_reg(sport, reg);
> +
> + return readl(addr);
> +}
> +
> +/* pic32 uart mode register bits */
> +#define PIC32_UART_MODE_ON (1 << 15)

BIT() ?

> +#define PIC32_UART_MODE_FRZ (1 << 14)
> +#define PIC32_UART_MODE_SIDL (1 << 13)
> +#define PIC32_UART_MODE_IREN (1 << 12)
> +#define PIC32_UART_MODE_RTSMD (1 << 11)
> +#define PIC32_UART_MODE_RESV1 (1 << 10)
> +#define PIC32_UART_MODE_UEN1 (1 << 9)
> +#define PIC32_UART_MODE_UEN0 (1 << 8)
> +#define PIC32_UART_MODE_WAKE (1 << 7)
> +#define PIC32_UART_MODE_LPBK (1 << 6)
> +#define PIC32_UART_MODE_ABAUD (1 << 5)
> +#define PIC32_UART_MODE_RXINV (1 << 4)
> +#define PIC32_UART_MODE_BRGH (1 << 3)
> +#define PIC32_UART_MODE_PDSEL1 (1 << 2)
> +#define PIC32_UART_MODE_PDSEL0 (1 << 1)
> +#define PIC32_UART_MODE_STSEL (1 << 0)
> +
> +/* pic32 uart status register bits */
> +#define PIC32_UART_STA_UTXISEL1 (1 << 15)
> +#define PIC32_UART_STA_UTXISEL0 (1 << 14)
> +#define PIC32_UART_STA_UTXINV (1 << 13)
> +#define PIC32_UART_STA_URXEN (1 << 12)
> +#define PIC32_UART_STA_UTXBRK (1 << 11)
> +#define PIC32_UART_STA_UTXEN (1 << 10)
> +#define PIC32_UART_STA_UTXBF (1 << 9)
> +#define PIC32_UART_STA_TRMT (1 << 8)
> +#define PIC32_UART_STA_URXISEL1 (1 << 7)
> +#define PIC32_UART_STA_URXISEL0 (1 << 6)
> +#define PIC32_UART_STA_ADDEN (1 << 5)
> +#define PIC32_UART_STA_RIDLE (1 << 4)
> +#define PIC32_UART_STA_PERR (1 << 3)
> +#define PIC32_UART_STA_FERR (1 << 2)
> +#define PIC32_UART_STA_OERR (1 << 1)
> +#define PIC32_UART_STA_URXDA (1 << 0)
> +
> +#endif /* __DT_PIC32_UART_H__ */
> diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
> index 93ba148..9df0a98 100644
> --- a/include/uapi/linux/serial_core.h
> +++ b/include/uapi/linux/serial_core.h
> @@ -261,4 +261,7 @@
> /* STM32 USART */
> #define PORT_STM32 113
>
> +/* Microchip PIC32 UART */
> +#define PORT_PIC32 114
> +
> #endif /* _UAPILINUX_SERIAL_CORE_H */
> --
> 1.7.9.5
>
> --
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--
With Best Regards,
Andy Shevchenko
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