[PATCH v5 2/2] tty/serial: atmel: add ISO7816 support

From: Ludovic Desroches
Date: Wed Sep 26 2018 - 09:02:46 EST

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From: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>

When mode is set in atmel_config_iso7816() we backup last RS232 mode
for coming back to this mode if requested.
Also allow setup of T=0 and T=1 parameter and basic support in set_termios
function as well.

Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
[ludovic.desroches@xxxxxxxxxxxxx: rebase, add check on fidi ratio, checkpatch fixes]
Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxxxxxx>
Acked-by: Richard Genoud <richard.genoud@xxxxxxxxx>
---
drivers/tty/serial/atmel_serial.c | 190 +++++++++++++++++++++++++++++++++++---
drivers/tty/serial/atmel_serial.h | 3 +-
2 files changed, 181 insertions(+), 12 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 267d4d1de3f8..05147fe24343 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -34,6 +34,7 @@
#include <linux/suspend.h>
#include <linux/mm.h>

+#include <asm/div64.h>
#include <asm/io.h>
#include <asm/ioctls.h>

@@ -147,6 +148,8 @@ struct atmel_uart_port {
struct circ_buf rx_ring;

struct mctrl_gpios *gpios;
+ u32 backup_mode; /* MR saved during iso7816 operations */
+ u32 backup_brgr; /* BRGR saved during iso7816 operations */
unsigned int tx_done_mask;
u32 fifo_size;
u32 rts_high;
@@ -163,6 +166,10 @@ struct atmel_uart_port {
unsigned int pending_status;
spinlock_t lock_suspended;

+ /* ISO7816 */
+ unsigned int fidi_min;
+ unsigned int fidi_max;
+
#ifdef CONFIG_PM
struct {
u32 cr;
@@ -361,6 +368,127 @@ static int atmel_config_rs485(struct uart_port *port,
return 0;
}

+static unsigned int atmel_calc_cd(struct uart_port *port,
+ struct serial_iso7816 *iso7816conf)
+{
+ struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+ unsigned int cd;
+ u64 mck_rate;
+
+ mck_rate = (u64)clk_get_rate(atmel_port->clk);
+ do_div(mck_rate, iso7816conf->clk);
+ cd = mck_rate;
+ return cd;
+}
+
+static unsigned int atmel_calc_fidi(struct uart_port *port,
+ struct serial_iso7816 *iso7816conf)
+{
+ u64 fidi = 0;
+
+ if (iso7816conf->sc_fi && iso7816conf->sc_di) {
+ fidi = (u64)iso7816conf->sc_fi;
+ do_div(fidi, iso7816conf->sc_di);
+ }
+ return (u32)fidi;
+}
+
+/* Enable or disable the iso7816 support */
+/* Called with interrupts disabled */
+static int atmel_config_iso7816(struct uart_port *port,
+ struct serial_iso7816 *iso7816conf)
+{
+ struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+ unsigned int mode;
+ unsigned int cd, fidi;
+ int ret = 0;
+
+ /* Disable interrupts */
+ atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
+
+ mode = atmel_uart_readl(port, ATMEL_US_MR);
+
+ if (iso7816conf->flags & SER_ISO7816_ENABLED) {
+ mode &= ~ATMEL_US_USMODE;
+
+ if (iso7816conf->tg > 255) {
+ dev_err(port->dev, "ISO7816: Timeguard exceeding 255\n");
+ memset(iso7816conf, 0, sizeof(struct serial_iso7816));
+ ret = -EINVAL;
+ goto err_out;
+ }
+
+ if ((iso7816conf->flags & SER_ISO7816_T_PARAM)
+ == SER_ISO7816_T(0)) {
+ mode |= ATMEL_US_USMODE_ISO7816_T0 | ATMEL_US_DSNACK;
+ } else if ((iso7816conf->flags & SER_ISO7816_T_PARAM)
+ == SER_ISO7816_T(1)) {
+ mode |= ATMEL_US_USMODE_ISO7816_T1 | ATMEL_US_INACK;
+ } else {
+ dev_err(port->dev, "ISO7816: Type not supported\n");
+ memset(iso7816conf, 0, sizeof(struct serial_iso7816));
+ ret = -EINVAL;
+ goto err_out;
+ }
+
+ mode &= ~(ATMEL_US_USCLKS | ATMEL_US_NBSTOP | ATMEL_US_PAR);
+
+ /* select mck clock, and output */
+ mode |= ATMEL_US_USCLKS_MCK | ATMEL_US_CLKO;
+ /* set parity for normal/inverse mode + max iterations */
+ mode |= ATMEL_US_PAR_EVEN | ATMEL_US_NBSTOP_1 | ATMEL_US_MAX_ITER(3);
+
+ cd = atmel_calc_cd(port, iso7816conf);
+ fidi = atmel_calc_fidi(port, iso7816conf);
+ if (fidi == 0) {
+ dev_warn(port->dev, "ISO7816 fidi = 0, Generator generates no signal\n");
+ } else if (fidi < atmel_port->fidi_min
+ || fidi > atmel_port->fidi_max) {
+ dev_err(port->dev, "ISO7816 fidi = %u, value not supported\n", fidi);
+ memset(iso7816conf, 0, sizeof(struct serial_iso7816));
+ ret = -EINVAL;
+ goto err_out;
+ }
+
+ if (!(port->iso7816.flags & SER_ISO7816_ENABLED)) {
+ /* port not yet in iso7816 mode: store configuration */
+ atmel_port->backup_mode = atmel_uart_readl(port, ATMEL_US_MR);
+ atmel_port->backup_brgr = atmel_uart_readl(port, ATMEL_US_BRGR);
+ }
+
+ atmel_uart_writel(port, ATMEL_US_TTGR, iso7816conf->tg);
+ atmel_uart_writel(port, ATMEL_US_BRGR, cd);
+ atmel_uart_writel(port, ATMEL_US_FIDI, fidi);
+
+ atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS | ATMEL_US_RXEN);
+ atmel_port->tx_done_mask = ATMEL_US_TXEMPTY | ATMEL_US_NACK | ATMEL_US_ITERATION;
+ } else {
+ dev_dbg(port->dev, "Setting UART back to RS232\n");
+ /* back to last RS232 settings */
+ mode = atmel_port->backup_mode;
+ memset(iso7816conf, 0, sizeof(struct serial_iso7816));
+ atmel_uart_writel(port, ATMEL_US_TTGR, 0);
+ atmel_uart_writel(port, ATMEL_US_BRGR, atmel_port->backup_brgr);
+ atmel_uart_writel(port, ATMEL_US_FIDI, 0x174);
+
+ if (atmel_use_pdc_tx(port))
+ atmel_port->tx_done_mask = ATMEL_US_ENDTX |
+ ATMEL_US_TXBUFE;
+ else
+ atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+ }
+
+ port->iso7816 = *iso7816conf;
+
+ atmel_uart_writel(port, ATMEL_US_MR, mode);
+
+err_out:
+ /* Enable interrupts */
+ atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);
+
+ return ret;
+}
+
/*
* Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
*/
@@ -480,8 +608,9 @@ static void atmel_stop_tx(struct uart_port *port)
/* Disable interrupts */
atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);

- if ((port->rs485.flags & SER_RS485_ENABLED) &&
- !(port->rs485.flags & SER_RS485_RX_DURING_TX))
+ if (((port->rs485.flags & SER_RS485_ENABLED) &&
+ !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
+ port->iso7816.flags & SER_ISO7816_ENABLED)
atmel_start_rx(port);
}

@@ -499,8 +628,9 @@ static void atmel_start_tx(struct uart_port *port)
return;

if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port))
- if ((port->rs485.flags & SER_RS485_ENABLED) &&
- !(port->rs485.flags & SER_RS485_RX_DURING_TX))
+ if (((port->rs485.flags & SER_RS485_ENABLED) &&
+ !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
+ port->iso7816.flags & SER_ISO7816_ENABLED)
atmel_stop_rx(port);

if (atmel_use_pdc_tx(port))
@@ -798,8 +928,9 @@ static void atmel_complete_tx_dma(void *arg)
*/
if (!uart_circ_empty(xmit))
atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
- else if ((port->rs485.flags & SER_RS485_ENABLED) &&
- !(port->rs485.flags & SER_RS485_RX_DURING_TX)) {
+ else if (((port->rs485.flags & SER_RS485_ENABLED) &&
+ !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
+ port->iso7816.flags & SER_ISO7816_ENABLED) {
/* DMA done, stop TX, start RX for RS485 */
atmel_start_rx(port);
}
@@ -1282,6 +1413,9 @@ atmel_handle_status(struct uart_port *port, unsigned int pending,
wake_up_interruptible(&port->state->port.delta_msr_wait);
}
}
+
+ if (pending & (ATMEL_US_NACK | ATMEL_US_ITERATION))
+ dev_dbg(port->dev, "ISO7816 ERROR (0x%08x)\n", pending);
}

/*
@@ -1374,8 +1508,9 @@ static void atmel_tx_pdc(struct uart_port *port)
atmel_uart_writel(port, ATMEL_US_IER,
atmel_port->tx_done_mask);
} else {
- if ((port->rs485.flags & SER_RS485_ENABLED) &&
- !(port->rs485.flags & SER_RS485_RX_DURING_TX)) {
+ if (((port->rs485.flags & SER_RS485_ENABLED) &&
+ !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
+ port->iso7816.flags & SER_ISO7816_ENABLED) {
/* DMA done, stop TX, start RX for RS485 */
atmel_start_rx(port);
}
@@ -1727,6 +1862,22 @@ static void atmel_get_ip_name(struct uart_port *port)
atmel_port->has_frac_baudrate = true;
atmel_port->has_hw_timer = true;
atmel_port->rtor = ATMEL_US_RTOR;
+ version = atmel_uart_readl(port, ATMEL_US_VERSION);
+ switch (version) {
+ case 0x814: /* sama5d2 */
+ /* fall through */
+ case 0x701: /* sama5d4 */
+ atmel_port->fidi_min = 3;
+ atmel_port->fidi_max = 65535;
+ break;
+ case 0x502: /* sam9x5, sama5d3 */
+ atmel_port->fidi_min = 3;
+ atmel_port->fidi_max = 2047;
+ break;
+ default:
+ atmel_port->fidi_min = 1;
+ atmel_port->fidi_max = 2047;
+ }
} else if (name == dbgu_uart) {
dev_dbg(port->dev, "Dbgu or uart without hw timer\n");
} else {
@@ -2100,6 +2251,17 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
atmel_uart_writel(port, ATMEL_US_TTGR,
port->rs485.delay_rts_after_send);
mode |= ATMEL_US_USMODE_RS485;
+ } else if (port->iso7816.flags & SER_ISO7816_ENABLED) {
+ atmel_uart_writel(port, ATMEL_US_TTGR, port->iso7816.tg);
+ /* select mck clock, and output */
+ mode |= ATMEL_US_USCLKS_MCK | ATMEL_US_CLKO;
+ /* set max iterations */
+ mode |= ATMEL_US_MAX_ITER(3);
+ if ((port->iso7816.flags & SER_ISO7816_T_PARAM)
+ == SER_ISO7816_T(0))
+ mode |= ATMEL_US_USMODE_ISO7816_T0;
+ else
+ mode |= ATMEL_US_USMODE_ISO7816_T1;
} else if (termios->c_cflag & CRTSCTS) {
/* RS232 with hardware handshake (RTS/CTS) */
if (atmel_use_fifo(port) &&
@@ -2176,7 +2338,8 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
}
quot = cd | fp << ATMEL_US_FP_OFFSET;

- atmel_uart_writel(port, ATMEL_US_BRGR, quot);
+ if (!(port->iso7816.flags & SER_ISO7816_ENABLED))
+ atmel_uart_writel(port, ATMEL_US_BRGR, quot);
atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);
atmel_port->tx_stopped = false;
@@ -2357,6 +2520,7 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port,
port->mapbase = mpdev->resource[0].start;
port->irq = mpdev->resource[1].start;
port->rs485_config = atmel_config_rs485;
+ port->iso7816_config = atmel_config_iso7816;
port->membase = NULL;

memset(&atmel_port->rx_ring, 0, sizeof(atmel_port->rx_ring));
@@ -2380,8 +2544,12 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port,
/* only enable clock when USART is in use */
}

- /* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
- if (port->rs485.flags & SER_RS485_ENABLED)
+ /*
+ * Use TXEMPTY for interrupt when rs485 or ISO7816 else TXRDY or
+ * ENDTX|TXBUFE
+ */
+ if (port->rs485.flags & SER_RS485_ENABLED ||
+ port->iso7816.flags & SER_ISO7816_ENABLED)
atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
else if (atmel_use_pdc_tx(port)) {
port->fifosize = PDC_BUFFER_SIZE;
diff --git a/drivers/tty/serial/atmel_serial.h b/drivers/tty/serial/atmel_serial.h
index ba3a2437cde4..d811d4f2d0c0 100644
--- a/drivers/tty/serial/atmel_serial.h
+++ b/drivers/tty/serial/atmel_serial.h
@@ -78,7 +78,8 @@
#define ATMEL_US_OVER BIT(19) /* Oversampling Mode */
#define ATMEL_US_INACK BIT(20) /* Inhibit Non Acknowledge */
#define ATMEL_US_DSNACK BIT(21) /* Disable Successive NACK */
-#define ATMEL_US_MAX_ITER GENMASK(26, 24) /* Max Iterations */
+#define ATMEL_US_MAX_ITER_MASK GENMASK(26, 24) /* Max Iterations */
+#define ATMEL_US_MAX_ITER(n) (((n) << 24) & ATMEL_US_MAX_ITER_MASK)
#define ATMEL_US_FILTER BIT(28) /* Infrared Receive Line Filter */

#define ATMEL_US_IER 0x08 /* Interrupt Enable Register */
--
2.12.2

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