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 = 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"); 193