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/reset.h> 15 #include <linux/slab.h> 16 17 #include "8250.h" 18 19 struct tegra_uart { 20 struct clk *clk; 21 struct reset_control *rst; 22 int line; 23 }; 24 25 static void tegra_uart_handle_break(struct uart_port *p) 26 { 27 unsigned int status, tmout = 10000; 28 29 while (1) { 30 status = p->serial_in(p, UART_LSR); 31 if (!(status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS))) 32 break; 33 34 p->serial_in(p, UART_RX); 35 36 if (--tmout == 0) 37 break; 38 udelay(1); 39 } 40 } 41 42 static int tegra_uart_probe(struct platform_device *pdev) 43 { 44 struct uart_8250_port port8250; 45 struct tegra_uart *uart; 46 struct uart_port *port; 47 struct resource *res; 48 int ret; 49 50 uart = devm_kzalloc(&pdev->dev, sizeof(*uart), GFP_KERNEL); 51 if (!uart) 52 return -ENOMEM; 53 54 memset(&port8250, 0, sizeof(port8250)); 55 56 port = &port8250.port; 57 spin_lock_init(&port->lock); 58 59 port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | 60 UPF_FIXED_TYPE; 61 port->iotype = UPIO_MEM32; 62 port->regshift = 2; 63 port->type = PORT_TEGRA; 64 port->irqflags |= IRQF_SHARED; 65 port->dev = &pdev->dev; 66 port->handle_break = tegra_uart_handle_break; 67 68 ret = of_alias_get_id(pdev->dev.of_node, "serial"); 69 if (ret >= 0) 70 port->line = ret; 71 72 ret = platform_get_irq(pdev, 0); 73 if (ret < 0) 74 return ret; 75 76 port->irq = ret; 77 78 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 79 if (!res) 80 return -ENODEV; 81 82 port->membase = devm_ioremap(&pdev->dev, res->start, 83 resource_size(res)); 84 if (!port->membase) 85 return -ENOMEM; 86 87 port->mapbase = res->start; 88 port->mapsize = resource_size(res); 89 90 uart->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL); 91 if (IS_ERR(uart->rst)) 92 return PTR_ERR(uart->rst); 93 94 if (device_property_read_u32(&pdev->dev, "clock-frequency", 95 &port->uartclk)) { 96 uart->clk = devm_clk_get(&pdev->dev, NULL); 97 if (IS_ERR(uart->clk)) { 98 dev_err(&pdev->dev, "failed to get clock!\n"); 99 return -ENODEV; 100 } 101 102 ret = clk_prepare_enable(uart->clk); 103 if (ret < 0) 104 return ret; 105 106 port->uartclk = clk_get_rate(uart->clk); 107 } 108 109 ret = reset_control_deassert(uart->rst); 110 if (ret) 111 goto err_clkdisable; 112 113 ret = serial8250_register_8250_port(&port8250); 114 if (ret < 0) 115 goto err_clkdisable; 116 117 platform_set_drvdata(pdev, uart); 118 uart->line = ret; 119 120 return 0; 121 122 err_clkdisable: 123 clk_disable_unprepare(uart->clk); 124 125 return ret; 126 } 127 128 static int tegra_uart_remove(struct platform_device *pdev) 129 { 130 struct tegra_uart *uart = platform_get_drvdata(pdev); 131 132 serial8250_unregister_port(uart->line); 133 reset_control_assert(uart->rst); 134 clk_disable_unprepare(uart->clk); 135 136 return 0; 137 } 138 139 #ifdef CONFIG_PM_SLEEP 140 static int tegra_uart_suspend(struct device *dev) 141 { 142 struct tegra_uart *uart = dev_get_drvdata(dev); 143 struct uart_8250_port *port8250 = serial8250_get_port(uart->line); 144 struct uart_port *port = &port8250->port; 145 146 serial8250_suspend_port(uart->line); 147 148 if (!uart_console(port) || console_suspend_enabled) 149 clk_disable_unprepare(uart->clk); 150 151 return 0; 152 } 153 154 static int tegra_uart_resume(struct device *dev) 155 { 156 struct tegra_uart *uart = dev_get_drvdata(dev); 157 struct uart_8250_port *port8250 = serial8250_get_port(uart->line); 158 struct uart_port *port = &port8250->port; 159 160 if (!uart_console(port) || console_suspend_enabled) 161 clk_prepare_enable(uart->clk); 162 163 serial8250_resume_port(uart->line); 164 165 return 0; 166 } 167 #endif 168 169 static SIMPLE_DEV_PM_OPS(tegra_uart_pm_ops, tegra_uart_suspend, 170 tegra_uart_resume); 171 172 static const struct of_device_id tegra_uart_of_match[] = { 173 { .compatible = "nvidia,tegra20-uart", }, 174 { }, 175 }; 176 MODULE_DEVICE_TABLE(of, tegra_uart_of_match); 177 178 static const struct acpi_device_id tegra_uart_acpi_match[] __maybe_unused = { 179 { "NVDA0100", 0 }, 180 { }, 181 }; 182 MODULE_DEVICE_TABLE(acpi, tegra_uart_acpi_match); 183 184 static struct platform_driver tegra_uart_driver = { 185 .driver = { 186 .name = "tegra-uart", 187 .pm = &tegra_uart_pm_ops, 188 .of_match_table = tegra_uart_of_match, 189 .acpi_match_table = ACPI_PTR(tegra_uart_acpi_match), 190 }, 191 .probe = tegra_uart_probe, 192 .remove = tegra_uart_remove, 193 }; 194 195 module_platform_driver(tegra_uart_driver); 196 197 MODULE_AUTHOR("Jeff Brasen <jbrasen@nvidia.com>"); 198 MODULE_DESCRIPTION("NVIDIA Tegra 8250 Driver"); 199 MODULE_LICENSE("GPL v2"); 200