diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_mtk.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_mtk.c | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c new file mode 100644 index 00000000000..8f37d57165e --- /dev/null +++ b/drivers/tty/serial/8250/8250_mtk.c @@ -0,0 +1,294 @@ +/* + * Mediatek 8250 driver. + * + * Copyright (c) 2014 MundoReader S.L. + * Author: Matthias Brugger <matthias.bgg@gmail.com> + * + * 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 <linux/clk.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of_irq.h> +#include <linux/of_platform.h> +#include <linux/platform_device.h> +#include <linux/pm_runtime.h> +#include <linux/serial_8250.h> +#include <linux/serial_reg.h> + +#include "8250.h" + +#define UART_MTK_HIGHS 0x09 /* Highspeed register */ +#define UART_MTK_SAMPLE_COUNT 0x0a /* Sample count register */ +#define UART_MTK_SAMPLE_POINT 0x0b /* Sample point register */ +#define MTK_UART_RATE_FIX 0x0d /* UART Rate Fix Register */ + +struct mtk8250_data { + int line; + struct clk *uart_clk; +}; + +static void +mtk8250_set_termios(struct uart_port *port, struct ktermios *termios, + struct ktermios *old) +{ + unsigned long flags; + unsigned int baud, quot; + + struct uart_8250_port *up = + container_of(port, struct uart_8250_port, port); + + serial8250_do_set_termios(port, termios, old); + + /* + * Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS) + * + * We need to recalcualte the quot register, as the claculation depends + * on the vaule in the highspeed register. + * + * Some baudrates are not supported by the chip, so we use the next + * lower rate supported and update termios c_flag. + * + * If highspeed register is set to 3, we need to specify sample count + * and sample point to increase accuracy. If not, we reset the + * registers to their default values. + */ + baud = uart_get_baud_rate(port, termios, old, + port->uartclk / 16 / 0xffff, + port->uartclk / 16); + + if (baud <= 115200) { + serial_port_out(port, UART_MTK_HIGHS, 0x0); + quot = uart_get_divisor(port, baud); + } else if (baud <= 576000) { + serial_port_out(port, UART_MTK_HIGHS, 0x2); + + /* Set to next lower baudrate supported */ + if ((baud == 500000) || (baud == 576000)) + baud = 460800; + quot = DIV_ROUND_CLOSEST(port->uartclk, 4 * baud); + } else { + serial_port_out(port, UART_MTK_HIGHS, 0x3); + + /* Set to highest baudrate supported */ + if (baud >= 1152000) + baud = 921600; + quot = DIV_ROUND_CLOSEST(port->uartclk, 256 * baud); + } + + /* + * Ok, we're now changing the port state. Do it with + * interrupts disabled. + */ + spin_lock_irqsave(&port->lock, flags); + + /* set DLAB we have cval saved in up->lcr from the call to the core */ + serial_port_out(port, UART_LCR, up->lcr | UART_LCR_DLAB); + serial_dl_write(up, quot); + + /* reset DLAB */ + serial_port_out(port, UART_LCR, up->lcr); + + if (baud > 460800) { + unsigned int tmp; + + tmp = DIV_ROUND_CLOSEST(port->uartclk, quot * baud); + serial_port_out(port, UART_MTK_SAMPLE_COUNT, tmp - 1); + serial_port_out(port, UART_MTK_SAMPLE_POINT, + (tmp - 2) >> 1); + } else { + serial_port_out(port, UART_MTK_SAMPLE_COUNT, 0x00); + serial_port_out(port, UART_MTK_SAMPLE_POINT, 0xff); + } + + spin_unlock_irqrestore(&port->lock, flags); + /* Don't rewrite B0 */ + if (tty_termios_baud_rate(termios)) + tty_termios_encode_baud_rate(termios, baud, baud); +} + +static void +mtk8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old) +{ + if (!state) + pm_runtime_get_sync(port->dev); + + serial8250_do_pm(port, state, old); + + if (state) + pm_runtime_put_sync_suspend(port->dev); +} + +static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p, + struct mtk8250_data *data) +{ + int err; + struct device_node *np = pdev->dev.of_node; + + data->uart_clk = of_clk_get(np, 0); + if (IS_ERR(data->uart_clk)) { + dev_warn(&pdev->dev, "Can't get timer clock\n"); + return PTR_ERR(data->uart_clk); + } + + err = clk_prepare_enable(data->uart_clk); + if (err) { + dev_warn(&pdev->dev, "Can't prepare clock\n"); + clk_put(data->uart_clk); + return err; + } + p->uartclk = clk_get_rate(data->uart_clk); + + return 0; +} + +static int mtk8250_probe(struct platform_device *pdev) +{ + struct uart_8250_port uart = {}; + struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0); + struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); + struct mtk8250_data *data; + int err; + + if (!regs || !irq) { + dev_err(&pdev->dev, "no registers/irq defined\n"); + return -EINVAL; + } + + uart.port.membase = devm_ioremap(&pdev->dev, regs->start, + resource_size(regs)); + if (!uart.port.membase) + return -ENOMEM; + + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + if (pdev->dev.of_node) { + err = mtk8250_probe_of(pdev, &uart.port, data); + if (err) + return err; + } else + return -ENODEV; + + spin_lock_init(&uart.port.lock); + uart.port.mapbase = regs->start; + uart.port.irq = irq->start; + uart.port.pm = mtk8250_do_pm; + uart.port.type = PORT_16550; + uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT; + uart.port.dev = &pdev->dev; + uart.port.iotype = UPIO_MEM32; + uart.port.regshift = 2; + uart.port.private_data = data; + uart.port.set_termios = mtk8250_set_termios; + + /* Disable Rate Fix function */ + writel(0x0, uart.port.membase + + (MTK_UART_RATE_FIX << uart.port.regshift)); + + data->line = serial8250_register_8250_port(&uart); + if (data->line < 0) + return data->line; + + platform_set_drvdata(pdev, data); + + pm_runtime_set_active(&pdev->dev); + pm_runtime_enable(&pdev->dev); + + return 0; +} + +static int mtk8250_remove(struct platform_device *pdev) +{ + struct mtk8250_data *data = platform_get_drvdata(pdev); + + pm_runtime_get_sync(&pdev->dev); + + serial8250_unregister_port(data->line); + if (!IS_ERR(data->uart_clk)) { + clk_disable_unprepare(data->uart_clk); + clk_put(data->uart_clk); + } + + pm_runtime_disable(&pdev->dev); + pm_runtime_put_noidle(&pdev->dev); + return 0; +} + +#ifdef CONFIG_PM_SLEEP +static int mtk8250_suspend(struct device *dev) +{ + struct mtk8250_data *data = dev_get_drvdata(dev); + + serial8250_suspend_port(data->line); + + return 0; +} + +static int mtk8250_resume(struct device *dev) +{ + struct mtk8250_data *data = dev_get_drvdata(dev); + + serial8250_resume_port(data->line); + + return 0; +} +#endif /* CONFIG_PM_SLEEP */ + +#ifdef CONFIG_PM_RUNTIME +static int mtk8250_runtime_suspend(struct device *dev) +{ + struct mtk8250_data *data = dev_get_drvdata(dev); + + if (!IS_ERR(data->uart_clk)) + clk_disable_unprepare(data->uart_clk); + + return 0; +} + +static int mtk8250_runtime_resume(struct device *dev) +{ + struct mtk8250_data *data = dev_get_drvdata(dev); + + if (!IS_ERR(data->uart_clk)) + clk_prepare_enable(data->uart_clk); + + return 0; +} +#endif + +static const struct dev_pm_ops mtk8250_pm_ops = { + SET_SYSTEM_SLEEP_PM_OPS(mtk8250_suspend, mtk8250_resume) + SET_RUNTIME_PM_OPS(mtk8250_runtime_suspend, mtk8250_runtime_resume, + NULL) +}; + +static const struct of_device_id mtk8250_of_match[] = { + { .compatible = "mediatek,mt6577-uart" }, + { /* Sentinel */ } +}; +MODULE_DEVICE_TABLE(of, mtk8250_of_match); + +static struct platform_driver mtk8250_platform_driver = { + .driver = { + .name = "mt6577-uart", + .pm = &mtk8250_pm_ops, + .of_match_table = mtk8250_of_match, + }, + .probe = mtk8250_probe, + .remove = mtk8250_remove, +}; +module_platform_driver(mtk8250_platform_driver); + +MODULE_AUTHOR("Matthias Brugger"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Mediatek 8250 serial port driver"); |