drivers/tty/serial/8250/8250_tegra.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  Serial Port driver for Tegra devices
   4  *
   5  *  Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
   6  */
   7
   8 #include <linux/acpi.h>
   9 #include <linux/clk.h>
  10 #include <linux/console.h>
  11 #include <linux/delay.h>
  12 #include <linux/io.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/reset.h>
  16 #include <linux/slab.h>
  17
  18 #include "8250.h"
  19
  20 struct tegra_uart {
  21         struct clk *clk;
  22         struct reset_control *rst;
  23         int line;
  24 };
  25
  26 static void tegra_uart_handle_break(struct uart_port *p)
  27 {
  28         unsigned int status, tmout = 10000;
  29
  30         while (1) {
  31                 status = p->serial_in(p, UART_LSR);
  32                 if (!(status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS)))
  33                         break;
  34
  35                 p->serial_in(p, UART_RX);
  36
  37                 if (--tmout == 0)
  38                         break;
  39                 udelay(1);
  40         }
  41 }
  42
  43 static int tegra_uart_probe(struct platform_device *pdev)
  44 {
  45         struct uart_8250_port port8250;
  46         struct tegra_uart *uart;
  47         struct uart_port *port;
  48         struct resource *res;
  49         int ret;
  50
  51         uart = devm_kzalloc(&pdev->dev, sizeof(*uart), GFP_KERNEL);
  52         if (!uart)
  53                 return -ENOMEM;
  54
  55         memset(&port8250, 0, sizeof(port8250));
  56
  57         port = &port8250.port;
  58         spin_lock_init(&port->lock);
  59
  60         port->flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_FIXED_TYPE;
  61         port->type = PORT_TEGRA;
  62         port->dev = &pdev->dev;
  63         port->handle_break = tegra_uart_handle_break;
  64
  65         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  66         if (!res)
  67                 return -ENODEV;
  68
  69         port->membase = devm_ioremap(&pdev->dev, res->start,
  70                                      resource_size(res));
  71         if (!port->membase)
  72                 return -ENOMEM;
  73
  74         port->mapbase = res->start;
  75         port->mapsize = resource_size(res);
  76
  77         ret = uart_read_port_properties(port);
  78         if (ret)
  79                 return ret;
  80
  81         port->iotype = UPIO_MEM32;
  82         port->regshift = 2;
  83
  84         uart->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
  85         if (IS_ERR(uart->rst))
  86                 return PTR_ERR(uart->rst);
  87
  88         if (!port->uartclk) {
  89                 uart->clk = devm_clk_get(&pdev->dev, NULL);
  90                 if (IS_ERR(uart->clk)) {
  91                         dev_err(&pdev->dev, "failed to get clock!\n");
  92                         return -ENODEV;
  93                 }
  94
  95                 ret = clk_prepare_enable(uart->clk);
  96                 if (ret < 0)
  97                         return ret;
  98
  99                 port->uartclk = clk_get_rate(uart->clk);
 100         }
 101
 102         ret = reset_control_deassert(uart->rst);
 103         if (ret)
 104                 goto err_clkdisable;
 105
 106         ret = serial8250_register_8250_port(&port8250);
 107         if (ret < 0)
 108                 goto err_ctrl_assert;
 109
 110         platform_set_drvdata(pdev, uart);
 111         uart->line = ret;
 112
 113         return 0;
 114
 115 err_ctrl_assert:
 116         reset_control_assert(uart->rst);
 117 err_clkdisable:
 118         clk_disable_unprepare(uart->clk);
 119
 120         return ret;
 121 }
 122
 123 static void tegra_uart_remove(struct platform_device *pdev)
 124 {
 125         struct tegra_uart *uart = platform_get_drvdata(pdev);
 126
 127         serial8250_unregister_port(uart->line);
 128         reset_control_assert(uart->rst);
 129         clk_disable_unprepare(uart->clk);
 130 }
 131
 132 #ifdef CONFIG_PM_SLEEP
 133 static int tegra_uart_suspend(struct device *dev)
 134 {
 135         struct tegra_uart *uart = dev_get_drvdata(dev);
 136         struct uart_8250_port *port8250 = serial8250_get_port(uart->line);
 137         struct uart_port *port = &port8250->port;
 138
 139         serial8250_suspend_port(uart->line);
 140
 141         if (!uart_console(port) || console_suspend_enabled)
 142                 clk_disable_unprepare(uart->clk);
 143
 144         return 0;
 145 }
 146
 147 static int tegra_uart_resume(struct device *dev)
 148 {
 149         struct tegra_uart *uart = dev_get_drvdata(dev);
 150         struct uart_8250_port *port8250 = serial8250_get_port(uart->line);
 151         struct uart_port *port = &port8250->port;
 152
 153         if (!uart_console(port) || console_suspend_enabled)
 154                 clk_prepare_enable(uart->clk);
 155
 156         serial8250_resume_port(uart->line);
 157
 158         return 0;
 159 }
 160 #endif
 161
 162 static SIMPLE_DEV_PM_OPS(tegra_uart_pm_ops, tegra_uart_suspend,
 163                          tegra_uart_resume);
 164
 165 static const struct of_device_id tegra_uart_of_match[] = {
 166         { .compatible = "nvidia,tegra20-uart", },
 167         { },
 168 };
 169 MODULE_DEVICE_TABLE(of, tegra_uart_of_match);
 170
 171 static const struct acpi_device_id tegra_uart_acpi_match[] __maybe_unused = {
 172         { "NVDA0100", 0 },
 173         { },
 174 };
 175 MODULE_DEVICE_TABLE(acpi, tegra_uart_acpi_match);
 176
 177 static struct platform_driver tegra_uart_driver = {
 178         .driver = {
 179                 .name = "tegra-uart",
 180                 .pm = &tegra_uart_pm_ops,
 181                 .of_match_table = tegra_uart_of_match,
 182                 .acpi_match_table = ACPI_PTR(tegra_uart_acpi_match),
 183         },
 184         .probe = tegra_uart_probe,
 185         .remove_new = tegra_uart_remove,
 186 };
 187
 188 module_platform_driver(tegra_uart_driver);
 189
 190 MODULE_AUTHOR("Jeff Brasen <jbrasen@nvidia.com>");
 191 MODULE_DESCRIPTION("NVIDIA Tegra 8250 Driver");
 192 MODULE_LICENSE("GPL v2");