[PATCH v3 2/2] spi: spi-pic32: Add PIC32 SPI master driver
From: Purna Chandra Mandal
Date: Sun Mar 06 2016 - 09:58:40 EST
The PIC32 SPI driver is capable of performing SPI transfers
using PIO or external DMA engine. GPIO controlled /CS support
is made default in the driver for correct operation of the
controller. This can be enabled by adding "cs-gpios" property
of the SPI node in board dts file.
Signed-off-by: Purna Chandra Mandal <purna.mandal@xxxxxxxxxxxxx>
---
Changes in v3:
- drop 'owner' field in driver struct.
- fix compilation warning in dma_addr_t print.
Changes in v2:
- drop internal function drain_rx_fifo()
- merge wrapper functions with callers wherever applicable
- sort includes alphabetically
- Kconfig: sort SPI_PIC32 alphabetically and add || COMPILE_TEST
- Makefile: sort SPI_PIC32 alphabetically
- replace cpu_relax() with ndelay() in disable_chip()
- drop spi controller driven /CS management completely, use only
GPIO controller /CS.
- rename function names starting with 'spi' to avoid namespace conflict
- use .one_transfer() callback instead of .one_message().
- drop /CS assert-deassert functions as core provides those.
- fix race while completing transfer before disabling interrupt.
drivers/spi/Kconfig | 6 +
drivers/spi/Makefile | 1 +
drivers/spi/spi-pic32.c | 1002 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 1009 insertions(+)
create mode 100644 drivers/spi/spi-pic32.c
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 7706416..22f973f 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -396,6 +396,12 @@ config SPI_ORION
help
This enables using the SPI master controller on the Orion chips.
+config SPI_PIC32
+ tristate "Microchip PIC32 series SPI"
+ depends on MACH_PIC32 || COMPILE_TEST
+ help
+ SPI driver for Microchip PIC32 SPI master controller.
+
config SPI_PL022
tristate "ARM AMBA PL022 SSP controller"
depends on ARM_AMBA
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 8991ffc..1bcb417 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -60,6 +60,7 @@ obj-$(CONFIG_SPI_OMAP_100K) += spi-omap-100k.o
obj-$(CONFIG_SPI_OMAP24XX) += spi-omap2-mcspi.o
obj-$(CONFIG_SPI_TI_QSPI) += spi-ti-qspi.o
obj-$(CONFIG_SPI_ORION) += spi-orion.o
+obj-$(CONFIG_SPI_PIC32) += spi-pic32.o
obj-$(CONFIG_SPI_PL022) += spi-pl022.o
obj-$(CONFIG_SPI_PPC4xx) += spi-ppc4xx.o
spi-pxa2xx-platform-objs := spi-pxa2xx.o
diff --git a/drivers/spi/spi-pic32.c b/drivers/spi/spi-pic32.c
new file mode 100644
index 0000000..009f3be
--- /dev/null
+++ b/drivers/spi/spi-pic32.c
@@ -0,0 +1,1002 @@
+/*
+ * Microchip PIC32 SPI controller driver.
+ *
+ * Purna Chandra Mandal <purna.mandal@xxxxxxxxxxxxx>
+ * Copyright (c) 2016, Microchip Technology Inc.
+ *
+ * This program is free software; you can distribute it and/or modify it
+ * under the terms of the GNU General Public License (Version 2) as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_gpio.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+
+/* SPI Register offsets */
+struct pic32_spi_regs {
+ u32 ctrl;
+ u32 ctrl_clr;
+ u32 ctrl_set;
+ u32 ctrl_inv;
+ u32 status;
+ u32 status_clr;
+ u32 status_set;
+ u32 status_inv;
+ u32 buf;
+ u32 reserved[3];
+ u32 baud;
+ u32 reserved2[3];
+ u32 ctrl2;
+ u32 ctrl2_clr;
+ u32 ctrl2_set;
+ u32 ctrl2_inv;
+};
+
+/* Bit fields in SPI Control Register */
+#define CTRL_RX_INT_SHIFT 0 /* Rx interrupt generation */
+#define RX_FIFO_EMTPY 0
+#define RX_FIFO_NOT_EMPTY 1 /* not empty */
+#define RX_FIFO_HALF_FULL 2 /* full by half or more */
+#define RX_FIFO_FULL 3 /* completely full */
+
+#define CTRL_TX_INT_SHIFT 2 /* TX interrupt generation */
+#define TX_FIFO_ALL_EMPTY 0 /* completely empty */
+#define TX_FIFO_EMTPY 1 /* empty */
+#define TX_FIFO_HALF_EMPTY 2 /* empty by half or more */
+#define TX_FIFO_NOT_FULL 3 /* atleast one empty */
+
+#define CTRL_MSTEN BIT(5) /* enable master mode */
+#define CTRL_CKP BIT(6) /* active low */
+#define CTRL_CKE BIT(8) /* Tx on falling edge */
+#define CTRL_SMP BIT(9) /* Rx at middle or end of tx */
+#define CTRL_BPW_MASK 0x03 /* bits per word/sample */
+#define CTRL_BPW_SHIFT 10
+#define PIC32_BPW_8 0
+#define PIC32_BPW_16 1
+#define PIC32_BPW_32 2
+#define CTRL_ON BIT(15) /* enable macro */
+#define CTRL_ENHBUF BIT(16) /* enable enhanced buffering */
+#define CTRL_MCLKSEL BIT(23) /* select clock source */
+#define CTRL_MSSEN BIT(28) /* macro driven /SS */
+#define CTRL_FRMEN BIT(31) /* enable framing mode */
+
+/* Bit fields in SPI Status Register */
+#define STAT_RF_EMPTY BIT(5) /* RX Fifo empty */
+#define STAT_RX_OV BIT(6) /* err, s/w needs to clear */
+#define STAT_TX_UR BIT(8) /* UR in Framed SPI modes */
+#define STAT_FRM_ERR BIT(12) /* Multiple Frame Sync pulse */
+#define STAT_TF_LVL_MASK 0x1F
+#define STAT_TF_LVL_SHIFT 16
+#define STAT_RF_LVL_MASK 0x1F
+#define STAT_RF_LVL_SHIFT 24
+
+/* Bit fields in Baud Register */
+#define BAUD_MASK 0x1ff
+
+/* Bit fields in Control2 Register */
+#define CTRL2_TX_UR_EN BIT(10) /* Enable int on Tx under-run */
+#define CTRL2_RX_OV_EN BIT(11) /* Enable int on Rx over-run */
+#define CTRL2_FRM_ERR_EN BIT(12) /* Enable frame err int */
+
+/* Minimum DMA transfer size */
+#define PIC32_DMA_LEN_MIN 64
+
+struct pic32_spi {
+ dma_addr_t dma_base;
+ struct pic32_spi_regs __iomem *regs;
+ int fault_irq;
+ int rx_irq;
+ int tx_irq;
+ u32 fifo_n_byte; /* FIFO depth in bytes */
+ struct clk *clk;
+ spinlock_t lock; /* lock */
+ struct spi_master *master;
+ /* Current SPI device specific */
+ struct spi_device *spi_dev;
+ u32 speed_hz; /* spi-clk rate */
+ u32 mode;
+#define PIC32F_XFER_PIO 0 /* do PIO transfer */
+#define PIC32F_DMA_PREP 1 /* DMA chnls configured */
+#define PIC32F_DMA_READY 2 /* buffer mapped and DMA issued */
+ unsigned long flags;
+ u32 fifo_n_elm; /* FIFO depth in words */
+ enum dma_slave_buswidth dma_width;
+ /* Current transfer state */
+ struct spi_message *mesg;
+ const void *tx;
+ const void *tx_end;
+ const void *rx;
+ const void *rx_end;
+ int len;
+ struct completion xfer_done;
+ /* SPI FiFo accessor */
+ void (*rx_fifo)(struct pic32_spi *);
+ void (*tx_fifo)(struct pic32_spi *);
+};
+
+static bool pic32_spi_debug;
+
+static void pic32_spi_enable_chip(struct pic32_spi *pic32s)
+{
+ writel(CTRL_ON, &pic32s->regs->ctrl_set);
+}
+
+static void pic32_spi_disable_chip(struct pic32_spi *pic32s)
+{
+ writel(CTRL_ON, &pic32s->regs->ctrl_clr);
+
+ /* avoid read/write to SPI register at immediate next CPU clock */
+ ndelay(20);
+}
+
+static void pic32_spi_set_clk_rate(struct pic32_spi *pic32s, u32 spi_ck)
+{
+ u32 div;
+
+ /* div = (clk_in / (2 * spi_ck)) - 1 */
+ div = DIV_ROUND_CLOSEST(clk_get_rate(pic32s->clk), 2 * spi_ck) - 1;
+
+ writel(div & BAUD_MASK, &pic32s->regs->baud);
+}
+
+static u32 pic32_rx_fifo_level(struct pic32_spi *pic32s)
+{
+ u32 sr = readl(&pic32s->regs->status);
+
+ return (sr >> STAT_RF_LVL_SHIFT) & STAT_RF_LVL_MASK;
+}
+
+static u32 pic32_tx_fifo_level(struct pic32_spi *pic32s)
+{
+ u32 sr = readl(&pic32s->regs->status);
+
+ return (sr >> STAT_TF_LVL_SHIFT) & STAT_TF_LVL_MASK;
+}
+
+/* Return the max entries we can fill into tx fifo */
+static u32 pic32_tx_max(struct pic32_spi *pic32s, int n_bytes)
+{
+ u32 tx_left, tx_room, rxtx_gap;
+
+ tx_left = (pic32s->tx_end - pic32s->tx) / n_bytes;
+ tx_room = pic32s->fifo_n_elm - pic32_tx_fifo_level(pic32s);
+
+ /*
+ * Another concern is about the tx/rx mismatch, we
+ * though to use (pic32s->fifo_n_byte - rxfl - txfl) as
+ * one maximum value for tx, but it doesn't cover the
+ * data which is out of tx/rx fifo and inside the
+ * shift registers. So a ctrl from sw point of
+ * view is taken.
+ */
+ rxtx_gap = ((pic32s->rx_end - pic32s->rx) -
+ (pic32s->tx_end - pic32s->tx)) / n_bytes;
+ return min3(tx_left, tx_room, (u32)(pic32s->fifo_n_elm - rxtx_gap));
+}
+
+/* Return the max entries we should read out of rx fifo */
+static u32 pic32_rx_max(struct pic32_spi *pic32s, int n_bytes)
+{
+ u32 rx_left = (pic32s->rx_end - pic32s->rx) / n_bytes;
+
+ return min_t(u32, rx_left, pic32_rx_fifo_level(pic32s));
+}
+
+#define BUILD_SPI_FIFO_RW(__name, __type, __bwl) \
+static void pic32_spi_rx_##__name(struct pic32_spi *pic32s) \
+{ \
+ __type v; \
+ u32 mx = pic32_rx_max(pic32s, sizeof(__type)); \
+ for (; mx; mx--) { \
+ v = read##__bwl(&pic32s->regs->buf); \
+ if (pic32s->rx_end - pic32s->len) \
+ *(__type *)(pic32s->rx) = v; \
+ pic32s->rx += sizeof(__type); \
+ } \
+} \
+ \
+static void pic32_spi_tx_##__name(struct pic32_spi *pic32s) \
+{ \
+ __type v; \
+ u32 mx = pic32_tx_max(pic32s, sizeof(__type)); \
+ for (; mx ; mx--) { \
+ v = (__type)~0U; \
+ if (pic32s->tx_end - pic32s->len) \
+ v = *(__type *)(pic32s->tx); \
+ write##__bwl(v, &pic32s->regs->buf); \
+ pic32s->tx += sizeof(__type); \
+ } \
+}
+
+BUILD_SPI_FIFO_RW(byte, u8, b);
+BUILD_SPI_FIFO_RW(word, u16, w);
+BUILD_SPI_FIFO_RW(dword, u32, l);
+
+static void pic32_err_stop(struct pic32_spi *pic32s, const char *msg)
+{
+ /* Stop h/w */
+ pic32_spi_disable_chip(pic32s);
+
+ /* disable all interrupts */
+ disable_irq_nosync(pic32s->fault_irq);
+ disable_irq_nosync(pic32s->rx_irq);
+ disable_irq_nosync(pic32s->tx_irq);
+
+ /* Show err message and abort xfer with err */
+ dev_err(&pic32s->master->dev, "%s\n", msg);
+ pic32s->mesg->status = -EIO;
+ complete(&pic32s->xfer_done);
+
+ dev_err(&pic32s->master->dev, "irq: disable all\n");
+}
+
+static irqreturn_t pic32_spi_fault_irq(int irq, void *dev_id)
+{
+ struct pic32_spi *pic32s = dev_id;
+ irqreturn_t ret = IRQ_HANDLED;
+ u32 status;
+
+ spin_lock(&pic32s->lock);
+
+ status = readl(&pic32s->regs->status);
+
+ /* Error handling */
+ if (status & (STAT_RX_OV | STAT_TX_UR)) {
+ writel(STAT_RX_OV, &pic32s->regs->status_clr);
+ writel(STAT_TX_UR, &pic32s->regs->status_clr);
+ pic32_err_stop(pic32s, "err_irq: fifo ov/ur-run\n");
+ goto exit_irq;
+ }
+
+ if (status & STAT_FRM_ERR) {
+ pic32_err_stop(pic32s, "err_irq: frame error");
+ goto exit_irq;
+ }
+
+ if (!pic32s->mesg) {
+ pic32_err_stop(pic32s, "err_irq: mesg error");
+ ret = IRQ_NONE;
+ goto exit_irq;
+ }
+
+exit_irq:
+ spin_unlock(&pic32s->lock);
+
+ return ret;
+}
+
+static irqreturn_t pic32_spi_rx_irq(int irq, void *dev_id)
+{
+ struct pic32_spi *pic32s = dev_id;
+
+ spin_lock(&pic32s->lock);
+
+ pic32s->rx_fifo(pic32s);
+
+ /* rx complete? */
+ if (pic32s->rx_end == pic32s->rx) {
+ /* mask & disable all interrupts */
+ disable_irq_nosync(pic32s->fault_irq);
+ disable_irq_nosync(pic32s->rx_irq);
+
+ /* complete current xfer */
+ complete(&pic32s->xfer_done);
+ }
+
+ spin_unlock(&pic32s->lock);
+
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t pic32_spi_tx_irq(int irq, void *dev_id)
+{
+ struct pic32_spi *pic32s = dev_id;
+
+ spin_lock(&pic32s->lock);
+
+ pic32s->tx_fifo(pic32s);
+
+ /* tx complete? mask and disable tx interrupt */
+ if (pic32s->tx_end == pic32s->tx)
+ disable_irq_nosync(pic32s->tx_irq);
+
+ spin_unlock(&pic32s->lock);
+
+ return IRQ_HANDLED;
+}
+
+static void pic32_spi_dma_rx_notify(void *data)
+{
+ struct pic32_spi *pic32s = data;
+
+ complete(&pic32s->xfer_done);
+}
+
+static int pic32_spi_poll_transfer(struct pic32_spi *pic32s,
+ unsigned long timeout)
+{
+ unsigned long deadline;
+
+ deadline = timeout + jiffies;
+ for (;;) {
+ pic32s->tx_fifo(pic32s);
+ cpu_relax();
+
+ pic32s->rx_fifo(pic32s);
+ cpu_relax();
+
+ /* received sufficient data */
+ if (pic32s->rx >= pic32s->rx_end)
+ break;
+
+ /* timedout ? */
+ if (time_after_eq(jiffies, deadline))
+ return -ETIMEDOUT;
+ }
+
+ return 0;
+}
+
+static int pic32_spi_dma_transfer(struct pic32_spi *pic32s,
+ struct spi_transfer *xfer)
+{
+ struct spi_master *master = pic32s->master;
+ struct dma_async_tx_descriptor *desc_rx;
+ struct dma_async_tx_descriptor *desc_tx;
+ dma_cookie_t cookie;
+ int ret;
+
+ if (!master->dma_rx || !master->dma_tx)
+ return -ENODEV;
+
+ desc_rx = dmaengine_prep_slave_sg(master->dma_rx,
+ xfer->rx_sg.sgl,
+ xfer->rx_sg.nents,
+ DMA_FROM_DEVICE,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc_rx) {
+ ret = -EINVAL;
+ goto err_dma;
+ }
+
+ desc_tx = dmaengine_prep_slave_sg(master->dma_tx,
+ xfer->tx_sg.sgl,
+ xfer->tx_sg.nents,
+ DMA_TO_DEVICE,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc_tx) {
+ ret = -EINVAL;
+ goto err_dma;
+ }
+
+ dev_vdbg(&master->dev, "dma_xfer %p: len %u, tx %p(0x%llx), rx %p(0x%llx)\n",
+ xfer, xfer->len, xfer->tx_buf, (u64)xfer->tx_dma,
+ xfer->rx_buf, (u64)xfer->rx_dma);
+
+ /* Put callback on the RX transfer, that should finish last */
+ desc_rx->callback = pic32_spi_dma_rx_notify;
+ desc_rx->callback_param = pic32s;
+
+ cookie = dmaengine_submit(desc_rx);
+ ret = dma_submit_error(cookie);
+ if (ret)
+ goto err_dma;
+
+ cookie = dmaengine_submit(desc_tx);
+ ret = dma_submit_error(cookie);
+ if (ret)
+ goto err_dma_tx;
+
+ dma_async_issue_pending(master->dma_rx);
+ dma_async_issue_pending(master->dma_tx);
+ set_bit(PIC32F_DMA_READY, &pic32s->flags);
+
+ return 0;
+
+err_dma_tx:
+ dmaengine_terminate_all(master->dma_rx);
+err_dma:
+ return ret;
+}
+
+static int pic32_spi_dma_config(struct pic32_spi *pic32s, u32 dma_width)
+{
+ int buf_offset = offsetof(struct pic32_spi_regs, buf);
+ struct spi_master *master = pic32s->master;
+ struct dma_slave_config cfg;
+ int err;
+
+ cfg.device_fc = true;
+ cfg.dst_addr = pic32s->dma_base + buf_offset;
+ cfg.dst_addr_width = dma_width;
+ cfg.dst_maxburst = pic32s->fifo_n_elm / 2; /* drain one-half */
+ cfg.src_addr = pic32s->dma_base + buf_offset;
+ cfg.src_addr_width = dma_width;
+ cfg.src_maxburst = pic32s->fifo_n_elm / 2; /* fill one-half */
+ cfg.slave_id = pic32s->tx_irq;
+ cfg.direction = DMA_MEM_TO_DEV;
+ err = dmaengine_slave_config(master->dma_tx, &cfg);
+ if (err) {
+ dev_err(&master->dev, "configure tx dma channel failed\n");
+ return err;
+ }
+
+ cfg.slave_id = pic32s->rx_irq;
+ cfg.direction = DMA_DEV_TO_MEM;
+ err = dmaengine_slave_config(master->dma_rx, &cfg);
+ if (err)
+ dev_err(&master->dev, "configure rx dma channel failed\n");
+
+ return err;
+}
+
+static void pic32_spi_set_word_size(struct pic32_spi *pic32s, u8 bits_per_word)
+{
+ enum dma_slave_buswidth dma_buswidth;
+ u32 spi_buswidth, v;
+
+ switch (bits_per_word) {
+ default:
+ case 8:
+ pic32s->rx_fifo = pic32_spi_rx_byte;
+ pic32s->tx_fifo = pic32_spi_tx_byte;
+ spi_buswidth = PIC32_BPW_8;
+ dma_buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ break;
+ case 16:
+ pic32s->rx_fifo = pic32_spi_rx_word;
+ pic32s->tx_fifo = pic32_spi_tx_word;
+ spi_buswidth = PIC32_BPW_16;
+ dma_buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
+ break;
+ case 32:
+ pic32s->rx_fifo = pic32_spi_rx_dword;
+ pic32s->tx_fifo = pic32_spi_tx_dword;
+ spi_buswidth = PIC32_BPW_32;
+ dma_buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;
+ break;
+ }
+
+ /* calculate maximum number of words fifos can hold */
+ pic32s->fifo_n_elm = DIV_ROUND_UP(pic32s->fifo_n_byte,
+ bits_per_word >> 3);
+ /* set word size */
+ v = readl(&pic32s->regs->ctrl);
+ v &= ~(CTRL_BPW_MASK << CTRL_BPW_SHIFT);
+ v |= spi_buswidth << CTRL_BPW_SHIFT;
+ writel(v, &pic32s->regs->ctrl);
+
+ /* re-configure dma width, if required */
+ if (test_bit(PIC32F_DMA_PREP, &pic32s->flags) &&
+ (dma_buswidth != pic32s->dma_width)) {
+ pic32_spi_dma_config(pic32s, dma_buswidth);
+ pic32s->dma_width = dma_buswidth;
+ }
+}
+
+static int pic32_spi_prepare_message(struct spi_master *master,
+ struct spi_message *msg)
+{
+ struct spi_device *spi = msg->spi;
+ struct spi_transfer *xfer;
+ struct pic32_spi *pic32s;
+
+ pic32s = spi_master_get_devdata(master);
+
+ pic32s->mesg = msg;
+ pic32_spi_disable_chip(pic32s);
+
+ if (!pic32_spi_debug)
+ return 0;
+
+ list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+ dev_dbg(&spi->dev, " xfer %p: len %u tx %p rx %p\n",
+ xfer, xfer->len, xfer->tx_buf, xfer->rx_buf);
+ print_hex_dump(KERN_DEBUG, "tx_buf ",
+ DUMP_PREFIX_ADDRESS,
+ 16, 1, xfer->tx_buf,
+ min_t(u32, xfer->len, 16), 1);
+ }
+
+ return 0;
+}
+
+static bool pic32_spi_can_dma(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *xfer)
+{
+ struct pic32_spi *pic32s = spi_master_get_devdata(master);
+
+ return (xfer->len >= PIC32_DMA_LEN_MIN) &&
+ test_bit(PIC32F_DMA_PREP, &pic32s->flags);
+}
+
+static int pic32_spi_one_transfer(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *transfer)
+{
+ struct pic32_spi *pic32s;
+ unsigned long flags;
+ int ret;
+
+ pic32s = spi_master_get_devdata(master);
+
+ /* set current transfer information */
+ pic32s->tx = (const void *)transfer->tx_buf;
+ pic32s->rx = (const void *)transfer->rx_buf;
+ pic32s->tx_end = pic32s->tx + transfer->len;
+ pic32s->rx_end = pic32s->rx + transfer->len;
+ pic32s->len = transfer->len;
+
+ if (transfer->speed_hz && (transfer->speed_hz != pic32s->speed_hz)) {
+ pic32_spi_set_clk_rate(pic32s, transfer->speed_hz);
+ pic32s->speed_hz = transfer->speed_hz;
+ }
+
+ if (transfer->bits_per_word)
+ pic32_spi_set_word_size(pic32s, transfer->bits_per_word);
+
+ pic32_spi_enable_chip(pic32s);
+ reinit_completion(&pic32s->xfer_done);
+
+ /* DMA transfer mode ? */
+ if (transfer->rx_sg.nents && transfer->tx_sg.nents) {
+ ret = pic32_spi_dma_transfer(pic32s, transfer);
+ if (ret) {
+ dev_err(&spi->dev, "dma submit error\n");
+ /* fallback: PIO transfer */
+ } else {
+ goto out_wait_for_xfer;
+ }
+ }
+
+ /* polling transfer mode */
+ if (test_bit(PIC32F_XFER_PIO, &pic32s->flags))
+ return pic32_spi_poll_transfer(pic32s, 2 * HZ);
+
+ /* interrupt driven PIO transfer */
+ spin_lock_irqsave(&pic32s->lock, flags);
+ enable_irq(pic32s->fault_irq);
+ enable_irq(pic32s->rx_irq);
+ enable_irq(pic32s->tx_irq);
+ spin_unlock_irqrestore(&pic32s->lock, flags);
+
+out_wait_for_xfer:
+ /* wait for completion */
+ ret = wait_for_completion_timeout(&pic32s->xfer_done, 2 * HZ);
+ if (ret <= 0) {
+ dev_err(&spi->dev, "wait timedout\n");
+ if (test_bit(PIC32F_DMA_READY, &pic32s->flags)) {
+ dmaengine_terminate_all(master->dma_rx);
+ dmaengine_terminate_all(master->dma_rx);
+ }
+ ret = -ETIMEDOUT;
+ } else {
+ ret = 0;
+ }
+
+ clear_bit(PIC32F_DMA_READY, &pic32s->flags);
+ return ret;
+}
+
+static int pic32_spi_unprepare_message(struct spi_master *master,
+ struct spi_message *msg)
+{
+ struct spi_transfer *xfer;
+ struct pic32_spi *pic32s;
+
+ pic32s = spi_master_get_devdata(master);
+
+ pic32_spi_disable_chip(pic32s);
+
+ if (!pic32_spi_debug)
+ return 0;
+
+ list_for_each_entry(xfer, &msg->transfers, transfer_list)
+ print_hex_dump(KERN_DEBUG, "rx_buf ",
+ DUMP_PREFIX_ADDRESS,
+ 16, 1, xfer->rx_buf,
+ min_t(u32, xfer->len, 32), 1);
+
+ return 0;
+}
+
+static void pic32_spi_cleanup(struct spi_device *spi)
+{
+ struct pic32_spi *pic32s;
+ int cs_high;
+
+ pic32s = spi_master_get_devdata(spi->master);
+
+ /* disable chip */
+ pic32_spi_disable_chip(pic32s);
+
+ /* release cs-gpio */
+ cs_high = pic32s->mode & SPI_CS_HIGH;
+ gpio_direction_output(spi->cs_gpio, !cs_high);
+ gpio_free(spi->cs_gpio);
+
+ /* reset reference */
+ pic32s->spi_dev = NULL;
+ pic32s->speed_hz = 0;
+}
+
+/* This may be called multiple times by same spi dev */
+static int pic32_spi_setup(struct spi_device *spi)
+{
+ struct pic32_spi *pic32s;
+ int cs_high, ret;
+ u32 v;
+
+ pic32s = spi_master_get_devdata(spi->master);
+
+ /* SPI master supports only one spi-device at a time.
+ * So multiple spi_setup() to different devices is not allowed.
+ */
+ if (unlikely(pic32s->spi_dev && (pic32s->spi_dev != spi))) {
+ dev_err(&spi->dev, "spi-master already associated with %s\n",
+ dev_name(&pic32s->spi_dev->dev));
+ return -EBUSY;
+ }
+
+ /* stop current transaction & release resource */
+ if (pic32s->spi_dev == spi)
+ pic32_spi_cleanup(spi);
+
+ pic32s->spi_dev = spi;
+
+ if (!spi->bits_per_word) {
+ dev_err(&spi->dev, "No bits_per_word defined\n");
+ return -EINVAL;
+ }
+
+ if (!spi->max_speed_hz) {
+ dev_err(&spi->dev, "No max speed HZ parameter\n");
+ return -EINVAL;
+ }
+
+ pic32_spi_disable_chip(pic32s);
+
+ pic32_spi_set_word_size(pic32s, spi->bits_per_word);
+
+ pic32s->speed_hz = spi->max_speed_hz;
+ pic32_spi_set_clk_rate(pic32s, spi->max_speed_hz);
+
+ /* set spi mode */
+ v = readl(&pic32s->regs->ctrl);
+
+ /* active low */
+ if (spi->mode & SPI_CPOL)
+ v |= CTRL_CKP;
+ else
+ v &= ~CTRL_CKP;
+
+ /* tx on rising edge */
+ if (spi->mode & SPI_CPHA)
+ v &= ~CTRL_CKE;
+ else
+ v |= CTRL_CKE;
+
+ /* rx at end of tx */
+ v |= CTRL_SMP;
+ writel(v, &pic32s->regs->ctrl);
+ pic32s->mode = spi->mode;
+
+ /* PIC32 spi ctrller can drive /SS during transfer depending
+ * on tx fifo fill-level. SS will stay asserted as long as TX
+ * fifo is non-empty, else will be deasserted confirming
+ * completion of the ongoing transfer.
+ * So we will force manual /SS handling by GPIO toggling.
+ */
+ if (!gpio_is_valid(spi->cs_gpio))
+ return -EINVAL;
+
+ cs_high = pic32s->mode & SPI_CS_HIGH;
+ ret = gpio_request(spi->cs_gpio, dev_name(&spi->dev));
+ if (!ret) {
+ gpio_direction_output(spi->cs_gpio, !cs_high);
+ dev_vdbg(&spi->dev,
+ "gpio-%d configured for spics (%s)\n",
+ spi->cs_gpio, cs_high ? "cs_high" : "cs_low");
+ }
+ writel(CTRL_MSSEN, &pic32s->regs->ctrl_clr);
+
+ dev_vdbg(&spi->master->dev,
+ "successfully registered spi-device %s\n",
+ dev_name(&spi->dev));
+ return 0;
+}
+
+static int pic32_spi_dma_prep(struct pic32_spi *pic32s, struct device *dev)
+{
+ struct spi_master *master = pic32s->master;
+ dma_cap_mask_t mask;
+ int err;
+
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_SLAVE, mask);
+
+ master->dma_rx = dma_request_slave_channel_compat(mask, NULL, NULL,
+ dev, "spi-rx");
+ if (!master->dma_rx) {
+ dev_err(dev, "RX channel not found, SPI unable to use DMA\n");
+ err = -EBUSY;
+ goto out_err;
+ }
+
+ master->dma_tx = dma_request_slave_channel_compat(mask, NULL, NULL,
+ dev, "spi-tx");
+ if (!master->dma_tx) {
+ dev_err(dev, "TX channel not found, SPI unable to use DMA\n");
+ err = -EBUSY;
+ goto out_err;
+ }
+
+ pic32s->dma_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ err = pic32_spi_dma_config(pic32s, pic32s->dma_width);
+ if (err)
+ goto out_err;
+
+ /* DMA chnls allocated and prepared */
+ set_bit(PIC32F_DMA_PREP, &pic32s->flags);
+
+ dev_dbg(dev, "Using %s (tx) and %s (rx) for DMA transfers\n",
+ dma_chan_name(master->dma_tx),
+ dma_chan_name(master->dma_rx));
+ return 0;
+
+out_err:
+ if (master->dma_rx)
+ dma_release_channel(master->dma_rx);
+
+ if (master->dma_tx)
+ dma_release_channel(master->dma_tx);
+
+ return err;
+}
+
+static void pic32_spi_dma_unprep(struct pic32_spi *pic32s)
+{
+ if (!test_bit(PIC32F_DMA_PREP, &pic32s->flags))
+ return;
+
+ clear_bit(PIC32F_DMA_PREP, &pic32s->flags);
+ if (pic32s->master->dma_rx)
+ dma_release_channel(pic32s->master->dma_rx);
+
+ if (pic32s->master->dma_tx)
+ dma_release_channel(pic32s->master->dma_tx);
+}
+
+static void pic32_spi_hw_init(struct pic32_spi *pic32s)
+{
+ u32 v;
+
+ /* disable module */
+ pic32_spi_disable_chip(pic32s);
+
+ v = readl(&pic32s->regs->ctrl);
+ /* enable enhanced fifo of 128bit deep */
+ v |= CTRL_ENHBUF;
+ pic32s->fifo_n_byte = 16;
+
+ /* disable framing mode */
+ v &= ~CTRL_FRMEN;
+
+ /* enable master mode while disabled */
+ v |= CTRL_MSTEN;
+
+ /* set tx fifo threshold interrupt */
+ v &= ~(0x3 << CTRL_TX_INT_SHIFT);
+ v |= (TX_FIFO_HALF_EMPTY << CTRL_TX_INT_SHIFT);
+
+ /* set rx fifo threshold interrupt */
+ v &= ~(0x3 << CTRL_RX_INT_SHIFT);
+ v |= (RX_FIFO_NOT_EMPTY << CTRL_RX_INT_SHIFT);
+
+ /* select clk source */
+ v &= ~CTRL_MCLKSEL;
+
+ writel(v, &pic32s->regs->ctrl);
+
+ /* enable error reporting */
+ v = CTRL2_TX_UR_EN | CTRL2_RX_OV_EN | CTRL2_FRM_ERR_EN;
+ writel(v, &pic32s->regs->ctrl2_set);
+}
+
+static int pic32_spi_hw_probe(struct platform_device *pdev,
+ struct pic32_spi *pic32s)
+{
+ struct resource *mem;
+ int ret;
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ pic32s->regs = devm_ioremap_resource(&pdev->dev, mem);
+ if (!pic32s->regs) {
+ dev_err(&pdev->dev, "mem map failed\n");
+ return -ENOMEM;
+ }
+ pic32s->dma_base = mem->start;
+
+ /* get irq resources: err-irq, rx-irq, tx-irq */
+ pic32s->fault_irq = platform_get_irq_byname(pdev, "fault");
+ if (pic32s->fault_irq < 0)
+ dev_warn(&pdev->dev, "no fault-irq found\n");
+
+ pic32s->rx_irq = platform_get_irq_byname(pdev, "rx");
+ if (pic32s->rx_irq < 0)
+ dev_warn(&pdev->dev, "no rx-irq found\n");
+
+ pic32s->tx_irq = platform_get_irq_byname(pdev, "tx");
+ if (pic32s->tx_irq < 0)
+ dev_warn(&pdev->dev, "no tx-irq found\n");
+
+ /* get clock */
+ pic32s->clk = devm_clk_get(&pdev->dev, "mck0");
+ if (IS_ERR(pic32s->clk)) {
+ dev_err(&pdev->dev, "err, no clk found\n");
+ ret = PTR_ERR(pic32s->clk);
+ goto err_unmap_mem;
+ }
+
+ ret = clk_prepare_enable(pic32s->clk);
+ if (ret)
+ goto err_unmap_mem;
+
+ /* initialize module */
+ pic32_spi_hw_init(pic32s);
+
+ return 0;
+
+err_unmap_mem:
+ dev_err(&pdev->dev, "hw_probe failed, ret %d\n", ret);
+ return ret;
+}
+
+static int pic32_spi_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct spi_master *master;
+ struct pic32_spi *pic32s;
+ int ret;
+
+ master = spi_alloc_master(dev, sizeof(*pic32s));
+ if (!master)
+ return -ENOMEM;
+
+ pic32s = spi_master_get_devdata(master);
+ pic32s->master = master;
+
+ ret = pic32_spi_hw_probe(pdev, pic32s);
+ if (ret) {
+ dev_err(&pdev->dev, "hw probe failed.\n");
+ goto err_free_master;
+ }
+
+ master->dev.of_node = of_node_get(pdev->dev.of_node);
+ master->mode_bits = SPI_MODE_3 | SPI_MODE_0 | SPI_CS_HIGH;
+ master->num_chipselect = 1; /* single chip-select */
+ master->max_speed_hz = clk_get_rate(pic32s->clk);
+ master->setup = pic32_spi_setup;
+ master->cleanup = pic32_spi_cleanup;
+ master->flags = SPI_MASTER_MUST_TX | SPI_MASTER_MUST_RX;
+ master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32);
+ master->prepare_message = pic32_spi_prepare_message;
+ master->transfer_one = pic32_spi_one_transfer;
+ master->unprepare_message = pic32_spi_unprepare_message;
+
+ /* DMA support */
+ ret = pic32_spi_dma_prep(pic32s, dev);
+ if (test_bit(PIC32F_DMA_PREP, &pic32s->flags))
+ master->can_dma = pic32_spi_can_dma;
+
+ init_completion(&pic32s->xfer_done);
+ spin_lock_init(&pic32s->lock);
+
+ /* install irq handlers (with irq-disabled) */
+ irq_set_status_flags(pic32s->fault_irq, IRQ_NOAUTOEN);
+ ret = devm_request_irq(dev, pic32s->fault_irq,
+ pic32_spi_fault_irq, IRQF_NO_THREAD,
+ dev_name(dev), pic32s);
+ if (ret < 0) {
+ dev_warn(dev, "request fault-irq %d\n", pic32s->rx_irq);
+ set_bit(PIC32F_XFER_PIO, &pic32s->flags);
+ goto irq_request_done;
+ }
+
+ /* receive interrupt handler */
+ irq_set_status_flags(pic32s->rx_irq, IRQ_NOAUTOEN);
+ ret = devm_request_irq(dev, pic32s->rx_irq,
+ pic32_spi_rx_irq, IRQF_NO_THREAD, dev_name(dev),
+ pic32s);
+ if (ret < 0) {
+ dev_warn(dev, "request rx-irq %d\n", pic32s->rx_irq);
+ set_bit(PIC32F_XFER_PIO, &pic32s->flags);
+ goto irq_request_done;
+ }
+
+ /* transmit interrupt handler */
+ irq_set_status_flags(pic32s->tx_irq, IRQ_NOAUTOEN);
+ ret = devm_request_irq(dev, pic32s->tx_irq,
+ pic32_spi_tx_irq, IRQF_NO_THREAD, dev_name(dev),
+ pic32s);
+ if (ret < 0) {
+ dev_warn(dev, "request tx-irq %d\n", pic32s->tx_irq);
+ set_bit(PIC32F_XFER_PIO, &pic32s->flags);
+ goto irq_request_done;
+ }
+
+irq_request_done:
+ /* register master */
+ ret = devm_spi_register_master(dev, master);
+ if (ret) {
+ dev_err(&master->dev, "failed registering spi master\n");
+ goto err_hw_remove;
+ }
+
+ platform_set_drvdata(pdev, pic32s);
+
+ return 0;
+
+err_hw_remove:
+ /* disable hw */
+ pic32_spi_disable_chip(pic32s);
+
+ /* disable clk */
+ if (!IS_ERR_OR_NULL(pic32s->clk))
+ clk_disable_unprepare(pic32s->clk);
+err_free_master:
+ spi_master_put(master);
+ return ret;
+}
+
+static int pic32_spi_remove(struct platform_device *pdev)
+{
+ struct pic32_spi *pic32s;
+
+ pic32s = platform_get_drvdata(pdev);
+ pic32_spi_disable_chip(pic32s);
+ clk_disable_unprepare(pic32s->clk);
+ pic32_spi_dma_unprep(pic32s);
+
+ return 0;
+}
+
+static const struct of_device_id pic32_spi_of_match[] = {
+ {.compatible = "microchip,pic32mzda-spi",},
+ {},
+};
+MODULE_DEVICE_TABLE(of, pic32_spi_of_match);
+
+static struct platform_driver pic32_spi_driver = {
+ .driver = {
+ .name = "spi-pic32",
+ .of_match_table = of_match_ptr(pic32_spi_of_match),
+ },
+ .probe = pic32_spi_probe,
+ .remove = pic32_spi_remove,
+};
+
+module_platform_driver(pic32_spi_driver);
+
+MODULE_AUTHOR("Purna Chandra Mandal <purna.mandal@xxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Microchip SPI driver for PIC32 SPI controller.");
+MODULE_LICENSE("GPL v2");
--
1.8.3.1