ARM: 6092/1: atmel_serial: support for RS485 communications

Final version of the patch that adds support for RS485 communications to the atmel_serial driver.

The patch has been already sent and discussed on both linux-kernel and linux-arm-kernel mailing lists several times.

Many people collaborated to improve and test the code:

Tested-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
Tested-by: Bernhard Roth <br@pwrnet.de>
Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
Signed-off-by: Rick Bronson <rick@efn.org>
Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/include/asm/ioctls.h b/arch/arm/include/asm/ioctls.h
index a91d8a1..7f0b6d1 100644 (file)
--- a/arch/arm/include/asm/ioctls.h
+++ b/arch/arm/include/asm/ioctls.h
@@ -53,6 +53,9 @@
 #define TIOCGPTN       _IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux device) */
 #define TIOCSPTLCK     _IOW('T',0x31, int)  /* Lock/unlock Pty */
 
+#define TIOCGRS485      0x542E
+#define TIOCSRS485      0x542F
+
 #define FIONCLEX       0x5450  /* these numbers need to be adjusted. */
 #define FIOCLEX                0x5451
 #define FIOASYNC       0x5452

diff --git a/arch/arm/mach-at91/include/mach/board.h b/arch/arm/mach-at91/include/mach/board.h
index ceaec6c..df2ed84 100644 (file)
--- a/arch/arm/mach-at91/include/mach/board.h
+++ b/arch/arm/mach-at91/include/mach/board.h
@@ -39,6 +39,7 @@
 #include <linux/usb/atmel_usba_udc.h>
 #include <linux/atmel-mci.h>
 #include <sound/atmel-ac97c.h>
+#include <linux/serial.h>
 
  /* USB Device */
 struct at91_udc_data {
@@ -143,9 +144,10 @@ extern struct platform_device *atmel_default_console_device;
 extern void __init __deprecated at91_init_serial(struct at91_uart_config *config);
 
 struct atmel_uart_data {
-       short           use_dma_tx;     /* use transmit DMA? */
-       short           use_dma_rx;     /* use receive DMA? */
-       void __iomem    *regs;          /* virtual base address, if any */
+       short                   use_dma_tx;     /* use transmit DMA? */
+       short                   use_dma_rx;     /* use receive DMA? */
+       void __iomem            *regs;          /* virt. base address, if any */
+       struct serial_rs485     rs485;          /* rs485 settings */
 };
 extern void __init at91_add_device_serial(void);
 

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 2c9bf9b..eed3c2d 100644 (file)
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -38,6 +38,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/atmel_pdc.h>
 #include <linux/atmel_serial.h>
+#include <linux/uaccess.h>
 
 #include <asm/io.h>
 
@@ -59,6 +60,9 @@
 
 #include <linux/serial_core.h>
 
+static void atmel_start_rx(struct uart_port *port);
+static void atmel_stop_rx(struct uart_port *port);
+
 #ifdef CONFIG_SERIAL_ATMEL_TTYAT
 
 /* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
@@ -93,6 +97,7 @@
 #define UART_GET_BRGR(port)    __raw_readl((port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_BRGR(port,v)  __raw_writel(v, (port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_RTOR(port,v)  __raw_writel(v, (port)->membase + ATMEL_US_RTOR)
+#define UART_PUT_TTGR(port, v) __raw_writel(v, (port)->membase + ATMEL_US_TTGR)
 
  /* PDC registers */
 #define UART_PUT_PTCR(port,v)  __raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
@@ -147,6 +152,9 @@ struct atmel_uart_port {
        unsigned int            irq_status_prev;
 
        struct circ_buf         rx_ring;
+
+       struct serial_rs485     rs485;          /* rs485 settings */
+       unsigned int            tx_done_mask;
 };
 
 static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
@@ -187,6 +195,46 @@ static bool atmel_use_dma_tx(struct uart_port *port)
 }
 #endif
 
+/* Enable or disable the rs485 support */
+void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
+{
+       struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+       unsigned int mode;
+
+       spin_lock(&port->lock);
+
+       /* Disable interrupts */
+       UART_PUT_IDR(port, atmel_port->tx_done_mask);
+
+       mode = UART_GET_MR(port);
+
+       /* Resetting serial mode to RS232 (0x0) */
+       mode &= ~ATMEL_US_USMODE;
+
+       atmel_port->rs485 = *rs485conf;
+
+       if (rs485conf->flags & SER_RS485_ENABLED) {
+               dev_dbg(port->dev, "Setting UART to RS485\n");
+               atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+               UART_PUT_TTGR(port, rs485conf->delay_rts_before_send);
+               mode |= ATMEL_US_USMODE_RS485;
+       } else {
+               dev_dbg(port->dev, "Setting UART to RS232\n");
+               if (atmel_use_dma_tx(port))
+                       atmel_port->tx_done_mask = ATMEL_US_ENDTX |
+                               ATMEL_US_TXBUFE;
+               else
+                       atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+       }
+       UART_PUT_MR(port, mode);
+
+       /* Enable interrupts */
+       UART_PUT_IER(port, atmel_port->tx_done_mask);
+
+       spin_unlock(&port->lock);
+
+}
+
 /*
  * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
  */
@@ -202,6 +250,7 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 {
        unsigned int control = 0;
        unsigned int mode;
+       struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 #ifdef CONFIG_ARCH_AT91RM9200
        if (cpu_is_at91rm9200()) {
@@ -236,6 +285,17 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
                mode |= ATMEL_US_CHMODE_LOC_LOOP;
        else
                mode |= ATMEL_US_CHMODE_NORMAL;
+
+       /* Resetting serial mode to RS232 (0x0) */
+       mode &= ~ATMEL_US_USMODE;
+
+       if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+               dev_dbg(port->dev, "Setting UART to RS485\n");
+               UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+               mode |= ATMEL_US_USMODE_RS485;
+       } else {
+               dev_dbg(port->dev, "Setting UART to RS232\n");
+       }
        UART_PUT_MR(port, mode);
 }
 
@@ -268,12 +328,17 @@ static u_int atmel_get_mctrl(struct uart_port *port)
  */
 static void atmel_stop_tx(struct uart_port *port)
 {
+       struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
        if (atmel_use_dma_tx(port)) {
                /* disable PDC transmit */
                UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
-               UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-       } else
-               UART_PUT_IDR(port, ATMEL_US_TXRDY);
+       }
+       /* Disable interrupts */
+       UART_PUT_IDR(port, atmel_port->tx_done_mask);
+
+       if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+               atmel_start_rx(port);
 }
 
 /*
@@ -281,17 +346,39 @@ static void atmel_stop_tx(struct uart_port *port)
  */
 static void atmel_start_tx(struct uart_port *port)
 {
+       struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
        if (atmel_use_dma_tx(port)) {
                if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
                        /* The transmitter is already running.  Yes, we
                           really need this.*/
                        return;
 
-               UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+               if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+                       atmel_stop_rx(port);
+
                /* re-enable PDC transmit */
                UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-       } else
-               UART_PUT_IER(port, ATMEL_US_TXRDY);
+       }
+       /* Enable interrupts */
+       UART_PUT_IER(port, atmel_port->tx_done_mask);
+}
+
+/*
+ * start receiving - port is in process of being opened.
+ */
+static void atmel_start_rx(struct uart_port *port)
+{
+       UART_PUT_CR(port, ATMEL_US_RSTSTA);  /* reset status and receiver */
+
+       if (atmel_use_dma_rx(port)) {
+               /* enable PDC controller */
+               UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+                       port->read_status_mask);
+               UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
+       } else {
+               UART_PUT_IER(port, ATMEL_US_RXRDY);
+       }
 }
 
 /*
@@ -302,9 +389,11 @@ static void atmel_stop_rx(struct uart_port *port)
        if (atmel_use_dma_rx(port)) {
                /* disable PDC receive */
                UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
-               UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
-       } else
+               UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+                       port->read_status_mask);
+       } else {
                UART_PUT_IDR(port, ATMEL_US_RXRDY);
+       }
 }
 
 /*
@@ -428,8 +517,9 @@ static void atmel_rx_chars(struct uart_port *port)
 static void atmel_tx_chars(struct uart_port *port)
 {
        struct circ_buf *xmit = &port->state->xmit;
+       struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-       if (port->x_char && UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+       if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
                UART_PUT_CHAR(port, port->x_char);
                port->icount.tx++;
                port->x_char = 0;
@@ -437,7 +527,7 @@ static void atmel_tx_chars(struct uart_port *port)
        if (uart_circ_empty(xmit) || uart_tx_stopped(port))
                return;
 
-       while (UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+       while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
                UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
                port->icount.tx++;
@@ -449,7 +539,8 @@ static void atmel_tx_chars(struct uart_port *port)
                uart_write_wakeup(port);
 
        if (!uart_circ_empty(xmit))
-               UART_PUT_IER(port, ATMEL_US_TXRDY);
+               /* Enable interrupts */
+               UART_PUT_IER(port, atmel_port->tx_done_mask);
 }
 
 /*
@@ -501,18 +592,10 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending)
 {
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-       if (atmel_use_dma_tx(port)) {
-               /* PDC transmit */
-               if (pending & (ATMEL_US_ENDTX | ATMEL_US_TXBUFE)) {
-                       UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-                       tasklet_schedule(&atmel_port->tasklet);
-               }
-       } else {
-               /* Interrupt transmit */
-               if (pending & ATMEL_US_TXRDY) {
-                       UART_PUT_IDR(port, ATMEL_US_TXRDY);
-                       tasklet_schedule(&atmel_port->tasklet);
-               }
+       if (pending & atmel_port->tx_done_mask) {
+               /* Either PDC or interrupt transmission */
+               UART_PUT_IDR(port, atmel_port->tx_done_mask);
+               tasklet_schedule(&atmel_port->tasklet);
        }
 }
 
@@ -590,9 +673,15 @@ static void atmel_tx_dma(struct uart_port *port)
 
                UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
                UART_PUT_TCR(port, count);
-               /* re-enable PDC transmit and interrupts */
+               /* re-enable PDC transmit */
                UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-               UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+               /* Enable interrupts */
+               UART_PUT_IER(port, atmel_port->tx_done_mask);
+       } else {
+               if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+                       /* DMA done, stop TX, start RX for RS485 */
+                       atmel_start_rx(port);
+               }
        }
 
        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
@@ -1017,6 +1106,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 {
        unsigned long flags;
        unsigned int mode, imr, quot, baud;
+       struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
        /* Get current mode register */
        mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
@@ -1115,6 +1205,17 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
        /* disable receiver and transmitter */
        UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
 
+       /* Resetting serial mode to RS232 (0x0) */
+       mode &= ~ATMEL_US_USMODE;
+
+       if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+               dev_dbg(port->dev, "Setting UART to RS485\n");
+               UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+               mode |= ATMEL_US_USMODE_RS485;
+       } else {
+               dev_dbg(port->dev, "Setting UART to RS232\n");
+       }
+
        /* set the parity, stop bits and data size */
        UART_PUT_MR(port, mode);
 
@@ -1231,6 +1332,35 @@ static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
 }
 #endif
 
+static int
+atmel_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
+{
+       struct serial_rs485 rs485conf;
+
+       switch (cmd) {
+       case TIOCSRS485:
+               if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg,
+                                       sizeof(rs485conf)))
+                       return -EFAULT;
+
+               atmel_config_rs485(port, &rs485conf);
+               break;
+
+       case TIOCGRS485:
+               if (copy_to_user((struct serial_rs485 *) arg,
+                                       &(to_atmel_uart_port(port)->rs485),
+                                       sizeof(rs485conf)))
+                       return -EFAULT;
+               break;
+
+       default:
+               return -ENOIOCTLCMD;
+       }
+       return 0;
+}
+
+
+
 static struct uart_ops atmel_pops = {
        .tx_empty       = atmel_tx_empty,
        .set_mctrl      = atmel_set_mctrl,
@@ -1250,6 +1380,7 @@ static struct uart_ops atmel_pops = {
        .config_port    = atmel_config_port,
        .verify_port    = atmel_verify_port,
        .pm             = atmel_serial_pm,
+       .ioctl          = atmel_ioctl,
 #ifdef CONFIG_CONSOLE_POLL
        .poll_get_char  = atmel_poll_get_char,
        .poll_put_char  = atmel_poll_put_char,
@@ -1265,13 +1396,12 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
        struct uart_port *port = &atmel_port->uart;
        struct atmel_uart_data *data = pdev->dev.platform_data;
 
-       port->iotype    = UPIO_MEM;
-       port->flags     = UPF_BOOT_AUTOCONF;
-       port->ops       = &atmel_pops;
-       port->fifosize  = 1;
-       port->line      = pdev->id;
-       port->dev       = &pdev->dev;
-
+       port->iotype            = UPIO_MEM;
+       port->flags             = UPF_BOOT_AUTOCONF;
+       port->ops               = &atmel_pops;
+       port->fifosize          = 1;
+       port->line              = pdev->id;
+       port->dev               = &pdev->dev;
        port->mapbase   = pdev->resource[0].start;
        port->irq       = pdev->resource[1].start;
 
@@ -1299,8 +1429,16 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 
        atmel_port->use_dma_rx = data->use_dma_rx;
        atmel_port->use_dma_tx = data->use_dma_tx;
-       if (atmel_use_dma_tx(port))
+       atmel_port->rs485       = data->rs485;
+       /* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
+       if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+               atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+       else if (atmel_use_dma_tx(port)) {
                port->fifosize = PDC_BUFFER_SIZE;
+               atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
+       } else {
+               atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+       }
 }
 
 /*
@@ -1334,6 +1472,7 @@ static void atmel_console_putchar(struct uart_port *port, int ch)
 static void atmel_console_write(struct console *co, const char *s, u_int count)
 {
        struct uart_port *port = &atmel_ports[co->index].uart;
+       struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        unsigned int status, imr;
        unsigned int pdc_tx;
 
@@ -1341,7 +1480,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
         * First, save IMR and then disable interrupts
         */
        imr = UART_GET_IMR(port);
-       UART_PUT_IDR(port, ATMEL_US_RXRDY | ATMEL_US_TXRDY);
+       UART_PUT_IDR(port, ATMEL_US_RXRDY | atmel_port->tx_done_mask);
 
        /* Store PDC transmit status and disable it */
        pdc_tx = UART_GET_PTSR(port) & ATMEL_PDC_TXTEN;