1 files changed, 88 insertions, 8 deletions

diff --git a/drivers/tty/serial/ar933x_uart.c b/drivers/tty/serial/ar933x_uart.c
index e4f60e2b87f3..505c490c0b44 100644
--- a/drivers/tty/serial/ar933x_uart.c
+++ b/drivers/tty/serial/ar933x_uart.c
@@ -25,11 +25,19 @@
 #include <linux/io.h>
 #include <linux/irq.h>
 
+#include <asm/div64.h>
+
 #include <asm/mach-ath79/ar933x_uart.h>
 #include <asm/mach-ath79/ar933x_uart_platform.h>
 
 #define DRIVER_NAME "ar933x-uart"
 
+#define AR933X_UART_MAX_SCALE   0xff
+#define AR933X_UART_MAX_STEP    0xffff
+
+#define AR933X_UART_MIN_BAUD    300
+#define AR933X_UART_MAX_BAUD    3000000
+
 #define AR933X_DUMMY_STATUS_RD  0x01
 
 static struct uart_driver ar933x_uart_driver;
@@ -37,6 +45,8 @@ static struct uart_driver ar933x_uart_driver;
 struct ar933x_uart_port {
         struct uart_port        port;
         unsigned int            ier;    /* shadow Interrupt Enable Register */
+        unsigned int            min_baud;
+        unsigned int            max_baud;
 };
 
 static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
@@ -162,6 +172,57 @@ static void ar933x_uart_enable_ms(struct uart_port *port)
 {
 }
 
+/*
+ * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
+ */
+static unsigned long ar933x_uart_get_baud(unsigned int clk,
+                                          unsigned int scale,
+                                          unsigned int step)
+{
+        u64 t;
+        u32 div;
+
+        div = (2 << 16) * (scale + 1);
+        t = clk;
+        t *= step;
+        t += (div / 2);
+        do_div(t, div);
+
+        return t;
+}
+
+static void ar933x_uart_get_scale_step(unsigned int clk,
+                                       unsigned int baud,
+                                       unsigned int *scale,
+                                       unsigned int *step)
+{
+        unsigned int tscale;
+        long min_diff;
+
+        *scale = 0;
+        *step = 0;
+
+        min_diff = baud;
+        for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
+                u64 tstep;
+                int diff;
+
+                tstep = baud * (tscale + 1);
+                tstep *= (2 << 16);
+                do_div(tstep, clk);
+
+                if (tstep > AR933X_UART_MAX_STEP)
+                        break;
+
+                diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
+                if (diff < min_diff) {
+                        min_diff = diff;
+                        *scale = tscale;
+                        *step = tstep;
+                }
+        }
+}
+
 static void ar933x_uart_set_termios(struct uart_port *port,
                                     struct ktermios *new,
                                     struct ktermios *old)
@@ -169,7 +230,7 @@ static void ar933x_uart_set_termios(struct uart_port *port,
         struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
         unsigned int cs;
         unsigned long flags;
-        unsigned int baud, scale;
+        unsigned int baud, scale, step;
 
         /* Only CS8 is supported */
         new->c_cflag &= ~CSIZE;
@@ -191,8 +252,8 @@ static void ar933x_uart_set_termios(struct uart_port *port,
         /* Mark/space parity is not supported */
         new->c_cflag &= ~CMSPAR;
 
-        baud = uart_get_baud_rate(port, new, old, 0, port->uartclk / 16);
-        scale = (port->uartclk / (16 * baud)) - 1;
+        baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud);
+        ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step);
 
         /*
          * Ok, we're now changing the port state. Do it with
@@ -200,6 +261,10 @@ static void ar933x_uart_set_termios(struct uart_port *port,
          */
         spin_lock_irqsave(&up->port.lock, flags);
 
+        /* disable the UART */
+        ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
+                      AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S);
+
         /* Update the per-port timeout. */
         uart_update_timeout(port, new->c_cflag, baud);
 
@@ -210,7 +275,7 @@ static void ar933x_uart_set_termios(struct uart_port *port,
                 up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD;
 
         ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
-                          scale << AR933X_UART_CLOCK_SCALE_S | 8192);
+                          scale << AR933X_UART_CLOCK_SCALE_S | step);
 
         /* setup configuration register */
         ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);
@@ -219,6 +284,11 @@ static void ar933x_uart_set_termios(struct uart_port *port,
         ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
                             AR933X_UART_CS_HOST_INT_EN);
 
+        /* reenable the UART */
+        ar933x_uart_rmw(up, AR933X_UART_CS_REG,
+                        AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
+                        AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S);
+
         spin_unlock_irqrestore(&up->port.lock, flags);
 
         if (tty_termios_baud_rate(new))
@@ -401,6 +471,8 @@ static void ar933x_uart_config_port(struct uart_port *port, int flags)
 static int ar933x_uart_verify_port(struct uart_port *port,
                                    struct serial_struct *ser)
 {
+        struct ar933x_uart_port *up = (struct ar933x_uart_port *) port;
+
         if (ser->type != PORT_UNKNOWN &&
             ser->type != PORT_AR933X)
                 return -EINVAL;
@@ -408,7 +480,8 @@ static int ar933x_uart_verify_port(struct uart_port *port,
         if (ser->irq < 0 || ser->irq >= NR_IRQS)
                 return -EINVAL;
 
-        if (ser->baud_base < 28800)
+        if (ser->baud_base < up->min_baud ||
+            ser->baud_base > up->max_baud)
                 return -EINVAL;
 
         return 0;
@@ -554,13 +627,14 @@ static struct uart_driver ar933x_uart_driver = {
         .cons           = AR933X_SERIAL_CONSOLE,
 };
 
-static int __devinit ar933x_uart_probe(struct platform_device *pdev)
+static int ar933x_uart_probe(struct platform_device *pdev)
 {
         struct ar933x_uart_platform_data *pdata;
         struct ar933x_uart_port *up;
         struct uart_port *port;
         struct resource *mem_res;
         struct resource *irq_res;
+        unsigned int baud;
         int id;
         int ret;
 
@@ -611,6 +685,12 @@ static int __devinit ar933x_uart_probe(struct platform_device *pdev)
         port->fifosize = AR933X_UART_FIFO_SIZE;
         port->ops = &ar933x_uart_ops;
 
+        baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
+        up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);
+
+        baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
+        up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);
+
         ar933x_uart_add_console_port(up);
 
         ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
@@ -627,7 +707,7 @@ err_free_up:
         return ret;
 }
 
-static int __devexit ar933x_uart_remove(struct platform_device *pdev)
+static int ar933x_uart_remove(struct platform_device *pdev)
 {
         struct ar933x_uart_port *up;
 
@@ -645,7 +725,7 @@ static int __devexit ar933x_uart_remove(struct platform_device *pdev)
 
 static struct platform_driver ar933x_uart_platform_driver = {
         .probe          = ar933x_uart_probe,
-        .remove         = __devexit_p(ar933x_uart_remove),
+        .remove         = ar933x_uart_remove,
         .driver         = {
                 .name           = DRIVER_NAME,
                 .owner          = THIS_MODULE,