diff options
Diffstat (limited to 'drivers/tty/serial/vt8500_serial.c')
| -rw-r--r-- | drivers/tty/serial/vt8500_serial.c | 27 |
1 files changed, 21 insertions, 6 deletions
diff --git a/drivers/tty/serial/vt8500_serial.c b/drivers/tty/serial/vt8500_serial.c index 4203862ef6cb..b2bc9e8ba048 100644 --- a/drivers/tty/serial/vt8500_serial.c +++ b/drivers/tty/serial/vt8500_serial.c @@ -101,12 +101,15 @@ #define VT8500_HAS_SWRTSCTS_SWITCH (1 << 1) +#define VT8500_RECOMMENDED_CLK 12000000 +#define VT8500_OVERSAMPLING_DIVISOR 13 #define VT8500_MAX_PORTS 6 struct vt8500_port { struct uart_port uart; char name[16]; struct clk *clk; + unsigned int clk_predivisor; unsigned int ier; unsigned int vt8500_uart_flags; }; @@ -311,20 +314,25 @@ static void vt8500_break_ctl(struct uart_port *port, int break_ctl) static int vt8500_set_baud_rate(struct uart_port *port, unsigned int baud) { + struct vt8500_port *vt8500_port = + container_of(port, struct vt8500_port, uart); unsigned long div; unsigned int loops = 1000; - div = vt8500_read(port, VT8500_URDIV) & ~(0x3ff); + div = ((vt8500_port->clk_predivisor - 1) & 0xf) << 16; + div |= (uart_get_divisor(port, baud) - 1) & 0x3ff; - if (unlikely((baud < 900) || (baud > 921600))) - div |= 7; - else - div |= (921600 / baud) - 1; + /* Effective baud rate */ + baud = port->uartclk / 16 / ((div & 0x3ff) + 1); while ((vt8500_read(port, VT8500_URUSR) & (1 << 5)) && --loops) cpu_relax(); + vt8500_write(port, div, VT8500_URDIV); + /* Break signal timing depends on baud rate, update accordingly */ + vt8500_write(port, mult_frac(baud, 4096, 1000000), VT8500_URBKR); + return baud; } @@ -691,6 +699,10 @@ static int vt8500_serial_probe(struct platform_device *pdev) } vt8500_port->vt8500_uart_flags = *flags; + vt8500_port->clk_predivisor = DIV_ROUND_CLOSEST( + clk_get_rate(vt8500_port->clk), + VT8500_RECOMMENDED_CLK + ); vt8500_port->uart.type = PORT_VT8500; vt8500_port->uart.iotype = UPIO_MEM; vt8500_port->uart.mapbase = mmres->start; @@ -701,7 +713,10 @@ static int vt8500_serial_probe(struct platform_device *pdev) vt8500_port->uart.dev = &pdev->dev; vt8500_port->uart.flags = UPF_IOREMAP | UPF_BOOT_AUTOCONF; - vt8500_port->uart.uartclk = clk_get_rate(vt8500_port->clk); + /* Serial core uses the magic "16" everywhere - adjust for it */ + vt8500_port->uart.uartclk = 16 * clk_get_rate(vt8500_port->clk) / + vt8500_port->clk_predivisor / + VT8500_OVERSAMPLING_DIVISOR; snprintf(vt8500_port->name, sizeof(vt8500_port->name), "VT8500 UART%d", pdev->id); |