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_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | 61 UPF_FIXED_TYPE; 62 port->iotype = UPIO_MEM32; 63 port->regshift = 2; 64 port->type = PORT_TEGRA; 65 port->irqflags |= IRQF_SHARED; 66 port->dev = &pdev->dev; 67 port->handle_break = tegra_uart_handle_break; 68 69 ret = of_alias_get_id(pdev->dev.of_node, "serial"); 70 if (ret >= 0) 71 port->line = ret; 72 73 ret = platform_get_irq(pdev, 0); 74 if (ret < 0) 75 return ret; 76 77 port->irq = ret; 78 79 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 80 if (!res) 81 return -ENODEV; 82 83 port->membase = devm_ioremap(&pdev->dev, res->start, 84 resource_size(res)); 85 if (!port->membase) 86 return -ENOMEM; 87 88 port->mapbase = res->start; 89 port->mapsize = resource_size(res); 90 91 uart->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL); 92 if (IS_ERR(uart->rst)) 93 return PTR_ERR(uart->rst); 94 95 if (device_property_read_u32(&pdev->dev, "clock-frequency", 96 &port->uartclk)) { 97 uart->clk = devm_clk_get(&pdev->dev, NULL); 98 if (IS_ERR(uart->clk)) { 99 dev_err(&pdev->dev, "failed to get clock!\n"); 100 return -ENODEV; 101 } 102 103 ret = clk_prepare_enable(uart->clk); 104 if (ret < 0) 105 return ret; 106 107 port->uartclk = clk_get_rate(uart->clk); 108 } 109 110 ret = reset_control_deassert(uart->rst); 111 if (ret) 112 goto err_clkdisable; 113 114 ret = serial8250_register_8250_port(&port8250); 115 if (ret < 0) 116 goto err_clkdisable; 117 118 platform_set_drvdata(pdev, uart); 119 uart->line = ret; 120 121 return 0; 122 123 err_clkdisable: 124 clk_disable_unprepare(uart->clk); 125 126 return ret; 127 } 128 129 static int tegra_uart_remove(struct platform_device *pdev) 130 { 131 struct tegra_uart *uart = platform_get_drvdata(pdev); 132 133 serial8250_unregister_port(uart->line); 134 reset_control_assert(uart->rst); 135 clk_disable_unprepare(uart->clk); 136 137 return 0; 138 } 139 140 #ifdef CONFIG_PM_SLEEP 141 static int tegra_uart_suspend(struct device *dev) 142 { 143 struct tegra_uart *uart = dev_get_drvdata(dev); 144 struct uart_8250_port *port8250 = serial8250_get_port(uart->line); 145 struct uart_port *port = &port8250->port; 146 147 serial8250_suspend_port(uart->line); 148 149 if (!uart_console(port) || console_suspend_enabled) 150 clk_disable_unprepare(uart->clk); 151 152 return 0; 153 } 154 155 static int tegra_uart_resume(struct device *dev) 156 { 157 struct tegra_uart *uart = dev_get_drvdata(dev); 158 struct uart_8250_port *port8250 = serial8250_get_port(uart->line); 159 struct uart_port *port = &port8250->port; 160 161 if (!uart_console(port) || console_suspend_enabled) 162 clk_prepare_enable(uart->clk); 163 164 serial8250_resume_port(uart->line); 165 166 return 0; 167 } 168 #endif 169 170 static SIMPLE_DEV_PM_OPS(tegra_uart_pm_ops, tegra_uart_suspend, 171 tegra_uart_resume); 172 173 static const struct of_device_id tegra_uart_of_match[] = { 174 { .compatible = "nvidia,tegra20-uart", }, 175 { }, 176 }; 177 MODULE_DEVICE_TABLE(of, tegra_uart_of_match); 178 179 static const struct acpi_device_id tegra_uart_acpi_match[] __maybe_unused = { 180 { "NVDA0100", 0 }, 181 { }, 182 }; 183 MODULE_DEVICE_TABLE(acpi, tegra_uart_acpi_match); 184 185 static struct platform_driver tegra_uart_driver = { 186 .driver = { 187 .name = "tegra-uart", 188 .pm = &tegra_uart_pm_ops, 189 .of_match_table = tegra_uart_of_match, 190 .acpi_match_table = ACPI_PTR(tegra_uart_acpi_match), 191 }, 192 .probe = tegra_uart_probe, 193 .remove = tegra_uart_remove, 194 }; 195 196 module_platform_driver(tegra_uart_driver); 197 198 MODULE_AUTHOR("Jeff Brasen <jbrasen@nvidia.com>"); 199 MODULE_DESCRIPTION("NVIDIA Tegra 8250 Driver"); 200 MODULE_LICENSE("GPL v2"); 201