diff options
Diffstat (limited to 'target/linux/ar71xx/patches-3.3/211-ar933x_uart-improve-serial-clock-calculation.patch')
| -rw-r--r-- | target/linux/ar71xx/patches-3.3/211-ar933x_uart-improve-serial-clock-calculation.patch | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/target/linux/ar71xx/patches-3.3/211-ar933x_uart-improve-serial-clock-calculation.patch b/target/linux/ar71xx/patches-3.3/211-ar933x_uart-improve-serial-clock-calculation.patch new file mode 100644 index 0000000000..510b75ed0f --- /dev/null +++ b/target/linux/ar71xx/patches-3.3/211-ar933x_uart-improve-serial-clock-calculation.patch @@ -0,0 +1,181 @@ +--- 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_dr + 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 + { + } + ++/* ++ * 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(stru + 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(stru + /* 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(stru + */ + 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(stru + 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(stru + 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(stru + 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(struc + 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; +@@ -561,6 +634,7 @@ static int __devinit ar933x_uart_probe(s + 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(s + 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); |