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Subject[PATCH 1/2] serial: imx: Add rs485 support to imx thanks to rs485 functions in serial_core
Date
This is a patch to add rs485 support with imx freescale processor
It allows to set the transmit pin used in the structure padding (rs485.padding[0])

Signed-off-by: Aurelien BOUIN <a.bouin@gmail.com>

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 4c5e909..a086eef 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -53,6 +53,8 @@
#include <asm/irq.h>
#include <linux/platform_data/serial-imx.h>
#include <linux/platform_data/dma-imx.h>
+#include <linux/uaccess.h>
+#include <linux/gpio.h>

/* Register definitions */
#define URXD0 0x0 /* Receiver Register */
@@ -280,6 +282,56 @@ static struct of_device_id imx_uart_dt_ids[] = {
};
MODULE_DEVICE_TABLE(of, imx_uart_dt_ids);

+static inline struct imx_port *to_imx_port(struct uart_port *uart)
+{
+ return container_of(uart, struct imx_port, port);
+}
+
+static void imx_rs485_stop_tx(struct imx_port *imx_uart_port)
+{
+ /*
+ * Deactivate transmit pin configured in the structure padding
+ */
+ gpio_set_value(imx_uart_port->port.rs485.padding[0], 0);
+}
+
+static void imx_rs485_start_tx(struct imx_port *imx_uart_port)
+{
+ /*
+ * Activate transmit pin configured in the structure padding
+ */
+ gpio_set_value(imx_uart_port->port.rs485.padding[0], 1);
+}
+
+/* Enable or disable the rs485 support */
+static int imx_config_rs485(struct uart_port *port,
+ struct serial_rs485 *rs485conf)
+{
+ port->rs485 = *rs485conf;
+ if (rs485conf->flags & SER_RS485_ENABLED) {
+ int ret;
+
+ dev_dbg(port->dev, "Setting UART /dev/ttymxc%d with the pin 0x%x to RS485\n",
+ port->line, port->rs485.padding[0]);
+ /*
+ * Set the transmit pin configured in the structure padding
+ * in GPIO output
+ */
+ ret = gpio_request(port->rs485.padding[0], "RS485 transmit");
+ if (ret)
+ dev_err(port->dev, "Unable to request the RS485 transmit %d\n",
+ port->rs485.padding[0]);
+ gpio_direction_output(port->rs485.padding[0], 0);
+
+ } else {
+ dev_dbg(port->dev, "Setting UART /dev/ttymxc%d to RS232\n",
+ port->line);
+ if (port->rs485.padding[0])
+ gpio_free(port->rs485.padding[0]);
+ }
+ return 0;
+}
+
static inline unsigned uts_reg(struct imx_port *sport)
{
return sport->devdata->uts_reg;
@@ -580,6 +632,15 @@ static void imx_start_tx(struct uart_port *port)
struct imx_port *sport = (struct imx_port *)port;
unsigned long temp;

+ if (port->rs485.flags & SER_RS485_ENABLED) {
+ imx_rs485_start_tx(sport);
+ /*
+ * Transmit complete interrupt change to receiver mode
+ */
+ temp = readl(sport->port.membase + UCR4);
+ writel(temp | UCR4_TCEN, sport->port.membase + UCR4);
+ }
+
if (USE_IRDA(sport)) {
/* half duplex in IrDA mode; have to disable receive mode */
temp = readl(sport->port.membase + UCR4);
@@ -693,8 +754,10 @@ static irqreturn_t imx_rxint(int irq, void *dev_id)
goto out;
continue;
}
-
- rx &= sport->port.read_status_mask;
+ /*
+ * Preserve characters with parity or framing errors
+ */
+ rx &= sport->port.read_status_mask | 0xFF;

if (rx & URXD_BRK)
flg = TTY_BREAK;
@@ -747,8 +810,30 @@ static irqreturn_t imx_int(int irq, void *dev_id)
struct imx_port *sport = dev_id;
unsigned int sts;
unsigned int sts2;
+ unsigned int cr1, cr2, cr3, cr4;

sts = readl(sport->port.membase + USR1);
+ sts2 = readl(sport->port.membase + USR2);
+ cr1 = readl(sport->port.membase + UCR1);
+ cr2 = readl(sport->port.membase + UCR2);
+ cr3 = readl(sport->port.membase + UCR3);
+ cr4 = readl(sport->port.membase + UCR4);
+
+ if (sport->port.rs485.flags & SER_RS485_ENABLED) {
+ /*
+ * Check if the transmit is complete
+ */
+ if ((cr4 & UCR4_TCEN) && (sts2 & USR2_TXDC)) {
+ unsigned long temp;
+
+ imx_rs485_stop_tx(sport);
+ /*
+ * Transmit complete interrupt disabled
+ */
+ temp = readl(sport->port.membase + UCR4);
+ writel(temp & ~UCR4_TCEN, sport->port.membase + UCR4);
+ }
+ }

if (sts & USR1_RRDY) {
if (sport->dma_is_enabled)
@@ -1072,6 +1157,17 @@ static int imx_startup(struct uart_port *port)
struct imx_port *sport = (struct imx_port *)port;
int retval, i;
unsigned long flags, temp;
+ int reset_time = 100;
+
+ /* reset fifo's and state machines to be sure
+ * to start the UART in correct conditions */
+ temp = readl(sport->port.membase + UCR2);
+ temp &= ~UCR2_SRST;
+ writel(temp, sport->port.membase + UCR2);
+ while (!(readl(sport->port.membase + UCR2) & UCR2_SRST) &&
+ (--reset_time > 0)) {
+ udelay(1);
+ }

retval = clk_prepare_enable(sport->clk_per);
if (retval)
@@ -1225,6 +1321,14 @@ static void imx_shutdown(struct uart_port *port)

writel(temp, sport->port.membase + UCR1);
spin_unlock_irqrestore(&sport->port.lock, flags);
+ /*
+ * Deactivate RS485 mode
+ */
+ if (port->rs485.flags & SER_RS485_ENABLED) {
+ imx_rs485_stop_tx(sport);
+ port->rs485.flags &= ~SER_RS485_ENABLED;
+ imx_config_rs485(port, &port->rs485);
+ }

clk_disable_unprepare(sport->clk_per);
clk_disable_unprepare(sport->clk_ipg);
@@ -1318,8 +1422,10 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
* Characters to ignore
*/
sport->port.ignore_status_mask = 0;
- if (termios->c_iflag & IGNPAR)
- sport->port.ignore_status_mask |= URXD_PRERR;
+ if (termios->c_iflag & IGNPAR) {
+ /* Ignore Framing errors when IGNPAR is set */
+ sport->port.ignore_status_mask |= URXD_PRERR | URXD_FRMERR;
+ }
if (termios->c_iflag & IGNBRK) {
sport->port.ignore_status_mask |= URXD_BRK;
/*
@@ -1560,8 +1666,8 @@ static void
imx_console_write(struct console *co, const char *s, unsigned int count)
{
struct imx_port *sport = imx_ports[co->index];
- struct imx_port_ucrs old_ucr;
unsigned int ucr1;
+ unsigned int old_ucr1, old_ucr2;
unsigned long flags = 0;
int locked = 1;
int retval;
@@ -1583,10 +1689,10 @@ imx_console_write(struct console *co, const char *s, unsigned int count)
spin_lock_irqsave(&sport->port.lock, flags);

/*
- * First, save UCR1/2/3 and then disable interrupts
+ * First, save UCR1/2 and then disable interrupts
*/
- imx_port_ucrs_save(&sport->port, &old_ucr);
- ucr1 = old_ucr.ucr1;
+ ucr1 = old_ucr1 = readl(sport->port.membase + UCR1);
+ old_ucr2 = readl(sport->port.membase + UCR2);

if (is_imx1_uart(sport))
ucr1 |= IMX1_UCR1_UARTCLKEN;
@@ -1595,17 +1701,18 @@ imx_console_write(struct console *co, const char *s, unsigned int count)

writel(ucr1, sport->port.membase + UCR1);

- writel(old_ucr.ucr2 | UCR2_TXEN, sport->port.membase + UCR2);
+ writel(old_ucr2 | UCR2_TXEN, sport->port.membase + UCR2);

uart_console_write(&sport->port, s, count, imx_console_putchar);

/*
* Finally, wait for transmitter to become empty
- * and restore UCR1/2/3
+ * and restore UCR1/2
*/
while (!(readl(sport->port.membase + USR2) & USR2_TXDC));

- imx_port_ucrs_restore(&sport->port, &old_ucr);
+ writel(old_ucr1, sport->port.membase + UCR1);
+ writel(old_ucr2, sport->port.membase + UCR2);

if (locked)
spin_unlock_irqrestore(&sport->port.lock, flags);
@@ -1873,6 +1980,7 @@ static int serial_imx_probe(struct platform_device *pdev)
sport->port.type = PORT_IMX,
sport->port.iotype = UPIO_MEM;
sport->port.irq = platform_get_irq(pdev, 0);
+ sport->port.rs485_config = imx_config_rs485;
sport->rxirq = platform_get_irq(pdev, 0);
sport->txirq = platform_get_irq(pdev, 1);
sport->rtsirq = platform_get_irq(pdev, 2);
--
1.9.1


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