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
tegra_uart_handle_break(struct uart_port * p)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
tegra_uart_probe(struct platform_device * pdev)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
tegra_uart_remove(struct platform_device * pdev)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
tegra_uart_suspend(struct device * dev)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
tegra_uart_resume(struct device * dev)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");
193