diff options
Diffstat (limited to 'drivers/serial/serial_ar933x.c')
| -rw-r--r-- | drivers/serial/serial_ar933x.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/drivers/serial/serial_ar933x.c b/drivers/serial/serial_ar933x.c new file mode 100644 index 0000000000..27cccba119 --- /dev/null +++ b/drivers/serial/serial_ar933x.c @@ -0,0 +1,204 @@ +/* + * based on linux.git/drivers/tty/serial/serial_ar933x.c + * + * See file CREDITS for list of people who contributed to this + * project. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + +#include <common.h> +#include <driver.h> +#include <init.h> +#include <malloc.h> +#include <io.h> +#include <asm-generic/div64.h> +#include <linux/clk.h> +#include <linux/err.h> + +#include "serial_ar933x.h" + +#define AR933X_UART_MAX_SCALE 0xff +#define AR933X_UART_MAX_STEP 0xffff + +struct ar933x_uart_priv { + void __iomem *base; + struct clk *clk; +}; + +static inline void ar933x_serial_writel(struct console_device *cdev, + u32 b, int offset) +{ + struct ar933x_uart_priv *priv = cdev->dev->priv; + + cpu_writel(b, priv->base + offset); +} + +static inline u32 ar933x_serial_readl(struct console_device *cdev, + int offset) +{ + struct ar933x_uart_priv *priv = cdev->dev->priv; + + return cpu_readl(priv->base + offset); +} + +/* + * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17)) + * take from linux. + */ +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 int ar933x_serial_setbaudrate(struct console_device *cdev, int baudrate) +{ + struct ar933x_uart_priv *priv = cdev->dev->priv; + unsigned int scale, step; + + ar933x_uart_get_scale_step(clk_get_rate(priv->clk), baudrate, &scale, + &step); + ar933x_serial_writel(cdev, (scale << AR933X_UART_CLOCK_SCALE_S) | step, + AR933X_UART_CLOCK_REG); + + return 0; +} + +static void ar933x_serial_putc(struct console_device *cdev, char ch) +{ + u32 data; + + /* wait transmitter ready */ + data = ar933x_serial_readl(cdev, AR933X_UART_DATA_REG); + while (!(data & AR933X_UART_DATA_TX_CSR)) + data = ar933x_serial_readl(cdev, AR933X_UART_DATA_REG); + + data = (ch & AR933X_UART_DATA_TX_RX_MASK) | AR933X_UART_DATA_TX_CSR; + ar933x_serial_writel(cdev, data, AR933X_UART_DATA_REG); +} + +static int ar933x_serial_tstc(struct console_device *cdev) +{ + u32 rdata; + + rdata = ar933x_serial_readl(cdev, AR933X_UART_DATA_REG); + + return rdata & AR933X_UART_DATA_RX_CSR; +} + +static int ar933x_serial_getc(struct console_device *cdev) +{ + u32 rdata; + + while (!ar933x_serial_tstc(cdev)) + ; + + rdata = ar933x_serial_readl(cdev, AR933X_UART_DATA_REG); + + /* remove the character from the FIFO */ + ar933x_serial_writel(cdev, AR933X_UART_DATA_RX_CSR, + AR933X_UART_DATA_REG); + + return rdata & AR933X_UART_DATA_TX_RX_MASK; +} + +static int ar933x_serial_probe(struct device_d *dev) +{ + struct console_device *cdev; + struct ar933x_uart_priv *priv; + u32 uart_cs; + + cdev = xzalloc(sizeof(struct console_device)); + priv = xzalloc(sizeof(struct ar933x_uart_priv)); + priv->base = dev_request_mem_region(dev, 0); + dev->priv = priv; + + cdev->dev = dev; + cdev->tstc = ar933x_serial_tstc; + cdev->putc = ar933x_serial_putc; + cdev->getc = ar933x_serial_getc; + cdev->setbrg = ar933x_serial_setbaudrate; + + priv->clk = clk_get(dev, NULL); + if (IS_ERR(priv->clk)) { + dev_err(dev, "unable to get UART clock\n"); + return PTR_ERR(priv->clk); + } + + uart_cs = (AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S) + | AR933X_UART_CS_TX_READY_ORIDE + | AR933X_UART_CS_RX_READY_ORIDE; + ar933x_serial_writel(cdev, uart_cs, AR933X_UART_CS_REG); + /* FIXME: need ar933x_serial_init_port(cdev); */ + + console_register(cdev); + + return 0; +} + +static struct of_device_id ar933x_serial_dt_ids[] = { + { + .compatible = "qca,ar9330-uart", + }, { + /* sentinel */ + }, +}; + +static struct driver_d ar933x_serial_driver = { + .name = "ar933x_serial", + .probe = ar933x_serial_probe, + .of_compatible = DRV_OF_COMPAT(ar933x_serial_dt_ids), +}; +console_platform_driver(ar933x_serial_driver); |