[PATCH v3 2/2] tty/serial: atmel: add ISO7816 support

[Ludovic Desroches]

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>
---
 drivers/tty/serial/atmel_serial.c | 211 +++++++++++++++++++++++++++++++++++---
 drivers/tty/serial/atmel_serial.h |   6 +-
 2 files changed, 201 insertions(+), 16 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 8e4428725848..4a7ec44b0ace 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>
 
@@ -83,6 +84,11 @@ static void atmel_stop_rx(struct uart_port *port);
 
 #define ATMEL_ISR_PASS_LIMIT	256
 
+struct atmel_uart_pdata {
+	unsigned int	fidi_min;
+	unsigned int	fidi_max;
+};
+
 struct atmel_dma_buffer {
 	unsigned char	*buf;
 	dma_addr_t	dma_addr;
@@ -114,6 +120,7 @@ struct atmel_uart_char {
  */
 struct atmel_uart_port {
 	struct uart_port	uart;		/* uart */
+	const struct atmel_uart_pdata *pdata;	/* SoC specific parameters */
 	struct clk		*clk;		/* uart clock */
 	int			may_wakeup;	/* cached value of device_may_wakeup for times we need to disable it */
 	u32			backup_imr;	/* IMR saved during suspend */
@@ -147,6 +154,8 @@ 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;
@@ -192,10 +201,34 @@ static struct console atmel_console;
 #endif
 
 #if defined(CONFIG_OF)
+static struct atmel_uart_pdata at91rm9200_pdata = {
+	.fidi_min = 1,
+	.fidi_max = 2047,
+};
+
+static struct atmel_uart_pdata at91sam9260_pdata = {
+	.fidi_min = 1,
+	.fidi_max = 2047,
+};
+
+static struct atmel_uart_pdata sama5d3_pdata = {
+	.fidi_min = 3,
+	.fidi_max = 65535,
+};
+
 static const struct of_device_id atmel_serial_dt_ids[] = {
-	{ .compatible = "atmel,at91rm9200-usart" },
-	{ .compatible = "atmel,at91sam9260-usart" },
-	{ /* sentinel */ }
+	{
+		.compatible = "atmel,at91rm9200-usart",
+		.data = &at91rm9200_pdata,
+	}, {
+		.compatible = "atmel,at91sam9260-usart",
+		.data = &at91sam9260_pdata,
+	}, {
+		.compatible = "atmel,sama5d3-usart",
+		.data = &sama5d3_pdata,
+	}, {
+		/* sentinel */
+	}
 };
 #endif
 
@@ -362,6 +395,127 @@ 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->pdata->fidi_min
+			   || fidi > atmel_port->pdata->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_FIDIR, 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_FIDIR, 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.
  */
@@ -481,8 +635,9 @@ 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);
 }
 
@@ -500,8 +655,9 @@ 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))
@@ -799,8 +955,9 @@ 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);
 	}
@@ -1281,6 +1438,9 @@ 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);
 }
 
 /*
@@ -1373,8 +1533,9 @@ 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);
 		}
@@ -2099,6 +2260,17 @@ 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) &&
@@ -2175,7 +2347,8 @@ 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;
@@ -2355,6 +2528,7 @@ static int atmel_init_port(struct atmel_uart_port *atmel_port,
 	port->mapbase	= pdev->resource[0].start;
 	port->irq	= pdev->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));
@@ -2378,8 +2552,12 @@ 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;
@@ -2719,6 +2897,11 @@ static int atmel_serial_probe(struct platform_device *pdev)
 	}
 
 	atmel_port = &atmel_ports[ret];
+	atmel_port->pdata = of_device_get_match_data(&pdev->dev);
+	if (!atmel_port->pdata) {
+		ret = -EINVAL;
+		goto err;
+	}
 	atmel_port->backup_imr = 0;
 	atmel_port->uart.line = ret;
 	atmel_serial_probe_fifos(atmel_port, pdev);
diff --git a/drivers/tty/serial/atmel_serial.h b/drivers/tty/serial/atmel_serial.h
index ba3a2437cde4..6911177964ad 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 */
@@ -124,7 +125,8 @@
 #define ATMEL_US_TTGR		0x28	/* Transmitter Timeguard Register */
 #define	ATMEL_US_TG		GENMASK(7, 0)	/* Timeguard Value */
 
-#define ATMEL_US_FIDI		0x40	/* FI DI Ratio Register */
+#define ATMEL_US_FIDIR		0x40	/* FI DI Ratio Register */
+#define ATMEL_US_FIDI		GENMASK(15, 0)	/* FIDI ratio */
 #define ATMEL_US_NER		0x44	/* Number of Errors Register */
 #define ATMEL_US_IF		0x4c	/* IrDA Filter Register */
 
-- 
2.12.2