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Date: Mon, 22 Mar 2010 10:55:48 +1300
From: Ryan Mallon <ryan@...ewatersys.com>
To: Claudio Scordino <claudio@...dence.eu.com>
CC: Linux Kernel <linux-kernel@...r.kernel.org>,
kernel@....linux.org.uk, Rick Bronson <rick@....org>,
John Nicholls <john@...nlinx.com>,
Sebastian Heutling <Sebastian.Heutling@...-ing.de>,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
michael trimarchi <michael@...dence.eu.com>,
alan@...rguk.ukuu.org.uk
Subject: Re: [PATCH] atmel_serial: Atmel RS485 support
Claudio Scordino wrote:
> Hi all,
>
> this is a patch to add RS485 support to the atmel_serial driver.
>
> The patch has been successfully tested by Sebastian Heutling (CC:-ed).
>
> Feedback (comments, suggestions, further testing) is welcome.
>
> Many thanks,
>
Ugh, not sure what happened to my previous email. It looked fine in
Thunderbird before I sent it. Hopefully this works a bit better:
> atmel_serial: RS485 support
>
> Signed-off-by: Claudio Scordino <claudio@...dence.eu.com>
> Signed-off-by: Michael Trimarchi <michael@...dence.eu.com>
> Signed-off-by: Rick Bronson <rick@....org>
> Signed-off-by: Sebastian Heutling <Sebastian.Heutling@...-ing.de>
> ---
> arch/arm/include/asm/ioctls.h | 2 +
> arch/arm/mach-at91/include/mach/board.h | 4 +
> drivers/serial/atmel_serial.c | 247
> ++++++++++++++++++++++++++-----
> 3 files changed, 218 insertions(+), 35 deletions(-)
>
> diff --git a/arch/arm/include/asm/ioctls.h b/arch/arm/include/asm/ioctls.h
> index a91d8a1..82f2177 100644
> --- a/arch/arm/include/asm/ioctls.h
> +++ b/arch/arm/include/asm/ioctls.h
> @@ -70,6 +70,8 @@
> #define TIOCGICOUNT 0x545D /* read serial port inline interrupt
> counts */
> #define FIOQSIZE 0x545E
>
> +#define TIOCSRS485 0x5461
> +
> /* Used for packet mode */
> #define TIOCPKT_DATA 0
> #define TIOCPKT_FLUSHREAD 1
> diff --git a/arch/arm/mach-at91/include/mach/board.h
> b/arch/arm/mach-at91/include/mach/board.h
> index ceaec6c..21f1308 100644
> --- 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 {
> @@ -146,6 +147,9 @@ 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 */
> + struct serial_rs485 rs485; /* this flag specifies
> + if the uart must be used
> + as RS485 */
> };
This comment is misleading, it is a struct not a flag. The comment should
say that it is the rs485 settings for the uart.
> extern void __init at91_add_device_serial(void);
>
> diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
> index 2c9bf9b..21bf3a8 100644
> --- 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);
Can you move these functions, so that these declarations are not needed?
> #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 +152,16 @@ struct atmel_uart_port {
> unsigned int irq_status_prev;
>
> struct circ_buf rx_ring;
> +
> + struct serial_rs485 rs485; /* this flag specifies
> + if the uart must be used
> + as RS485 */
> + /* Fields related to interrupts:
> + if (rs485) = ATMEL_US_TXEMPTY
> + else if (use_dma_tx) = ATMEL_US_ENDTX | ATMEL_US_TXBUFE
> + else = ATMEL_US_TXRDY;
> + */
This comment doesn't really belong here. Also, please use *s at the
beginning of each line in a multiline comment.
> + unsigned int tx_done_mask;
> };
>
> static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
> @@ -187,6 +202,85 @@ static bool atmel_use_dma_tx(struct uart_port *port)
> }
> #endif
>
> +/* Enable or disable the rs485 support */
> +void atmel_enable_disable_rs485(struct uart_port *port, struct
> serial_rs485 *rs485conf)
> +{
Please change the name of this function. Something like
atmel_config_rs485 would be better.
> + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> + unsigned long flags;
> + unsigned int mode;
> +
> + spin_lock_irqsave(&port->lock, flags);
> +
> + 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)) {
Reversing the logic of this if statement will make it slightly easier to
read.
> + 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;
> + } else {
> + 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;
> + }
> + UART_PUT_MR(port, mode);
> +
> + spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +
> +static ssize_t show_rs485(struct device *dev, struct device_attribute
> *attr, \
> + char *buf)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct uart_port *port = platform_get_drvdata(pdev);
> + unsigned int current_mode;
> +
> + current_mode = UART_GET_MR(port);
> + current_mode &= ATMEL_US_USMODE;
current_mode = UART_GET_MR(port) & ATMEL_US_USMODE;
> + return snprintf(buf, PAGE_SIZE, "%u\n", current_mode);
> +}
> +
> +static ssize_t set_rs485(struct device *dev, struct device_attribute
> *attr, \
> + const char *buf, size_t len)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct uart_port *port = platform_get_drvdata(pdev);
> + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> + struct serial_rs485 rs485conf = atmel_port->rs485;
> + unsigned int value;
> +
> + if (buf == NULL)
> + goto err;
if (!buf)
return -EINVAL;
> +
> + value = simple_strtoul(buf, NULL, 10);
> +
> + if ((value != 0) && (value != 1))
> + goto err;
Is there any reason to be so strict on the values, you could just do this:
value = !!(simple_strtoul(buf, NULL, 0));
which will allow the user to use values in any base, and will convert any
non-zero values to 1.
> +
> + if (!value) {
Again, I would revert the logic of this if statement.
> + rs485conf.flags &= ~(SER_RS485_ENABLED);
> + } else {
> + rs485conf.flags |= SER_RS485_ENABLED;
> + /* 0x4 is the normal reset value. */
> + rs485conf.delay_rts_before_send = 0x00000004;
> + }
> +
> + atmel_enable_disable_rs485(port, &rs485conf);
> +
> +err:
> + return strnlen(buf, PAGE_SIZE);
> +}
> +
> +static DEVICE_ATTR(rs485, 0644, show_rs485, set_rs485);
> +
> /*
> * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
> */
> @@ -202,6 +296,7 @@ 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 +331,16 @@ 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, "Keeping 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, "Keeping UART to RS232\n");
> UART_PUT_MR(port, mode);
> }
>
> @@ -268,12 +373,17 @@ 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 +391,22 @@ 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);
> }
>
> /*
> @@ -302,12 +417,28 @@ 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);
> + UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
> port->read_status_mask);
This line, and a couple of others, extend over 80 characters. Could you
please split them up.
> } else
> UART_PUT_IDR(port, ATMEL_US_RXRDY);
Please use braces for single line else statements when the if clause has
braces.
> }
>
> /*
> + * 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);
> +}
> +
> +
> +/*
> * Enable modem status interrupts
> */
> static void atmel_enable_ms(struct uart_port *port)
> @@ -428,8 +559,9 @@ 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 +569,7 @@ 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 +581,8 @@ 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 +634,10 @@ 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 +715,15 @@ 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 +1148,7 @@ 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 +1247,16 @@ 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, "Keeping 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, "Keeping UART to RS232\n");
> +
> /* set the parity, stop bits and data size */
> UART_PUT_MR(port, mode);
>
> @@ -1231,6 +1373,31 @@ 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)
> +{
> +
> + switch (cmd) {
> + case TIOCSRS485:
> + {
> + struct serial_rs485 rs485conf;
If you move this declaration to the top of the function you will save
two levels of indentation.
Is it necessary to have both an ioctl and a sysfs control for putting
the uart into rs485 mode? The ioctl is more standardised, so perhaps
drop the sysfs control?
> + if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg,
> + sizeof(rs485conf)))
> + return -EFAULT;
> +
> + dev_dbg(port->dev, "enable e/o disable rs485\n");
> +
> + atmel_enable_disable_rs485(port, &rs485conf);
> + }
> + break;
> +
> + default:
> + return -ENOIOCTLCMD;
> + }
> + return 0;
> +}
> +
> +
> +
> static struct uart_ops atmel_pops = {
> .tx_empty = atmel_tx_empty,
> .set_mctrl = atmel_set_mctrl,
> @@ -1250,6 +1417,7 @@ 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 +1433,12 @@ 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 +1466,15 @@ 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 +1508,7 @@ 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 +1516,7 @@ 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;
> @@ -1355,7 +1530,7 @@ static void atmel_console_write(struct console
> *co, const char *s, u_int count)
> */
> do {
> status = UART_GET_CSR(port);
> - } while (!(status & ATMEL_US_TXRDY));
> + } while (!(status & atmel_port->tx_done_mask));
>
> /* Restore PDC transmit status */
> if (pdc_tx)
> @@ -1587,7 +1762,7 @@ static int __devinit atmel_serial_probe(struct
> platform_device *pdev)
> device_init_wakeup(&pdev->dev, 1);
> platform_set_drvdata(pdev, port);
>
> - return 0;
> + return device_create_file(&(pdev->dev), &dev_attr_rs485);
>
> err_add_port:
> kfree(port->rx_ring.buf);
> @@ -1619,6 +1794,8 @@ static int __devexit atmel_serial_remove(struct
> platform_device *pdev)
>
> clk_put(atmel_port->clk);
>
> + device_remove_file(&(pdev->dev), &dev_attr_rs485);
> +
> return ret;
> }
>
> --
> 1.6.0.4
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