1c6825c63SJeff Brasen // SPDX-License-Identifier: GPL-2.0+
2c6825c63SJeff Brasen /*
3c6825c63SJeff Brasen * Serial Port driver for Tegra devices
4c6825c63SJeff Brasen *
5c6825c63SJeff Brasen * Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
6c6825c63SJeff Brasen */
7c6825c63SJeff Brasen
8c6825c63SJeff Brasen #include <linux/acpi.h>
9c6825c63SJeff Brasen #include <linux/clk.h>
10c6825c63SJeff Brasen #include <linux/console.h>
11c6825c63SJeff Brasen #include <linux/delay.h>
12c6825c63SJeff Brasen #include <linux/io.h>
13c6825c63SJeff Brasen #include <linux/module.h>
14933c9f19SRob Herring #include <linux/of.h>
15c6825c63SJeff Brasen #include <linux/reset.h>
16c6825c63SJeff Brasen #include <linux/slab.h>
17c6825c63SJeff Brasen
18c6825c63SJeff Brasen #include "8250.h"
19c6825c63SJeff Brasen
20c6825c63SJeff Brasen struct tegra_uart {
21c6825c63SJeff Brasen struct clk *clk;
22c6825c63SJeff Brasen struct reset_control *rst;
23c6825c63SJeff Brasen int line;
24c6825c63SJeff Brasen };
25c6825c63SJeff Brasen
tegra_uart_handle_break(struct uart_port * p)26c6825c63SJeff Brasen static void tegra_uart_handle_break(struct uart_port *p)
27c6825c63SJeff Brasen {
28c6825c63SJeff Brasen unsigned int status, tmout = 10000;
29c6825c63SJeff Brasen
307d7dec45SJiri Slaby while (1) {
31c6825c63SJeff Brasen status = p->serial_in(p, UART_LSR);
327d7dec45SJiri Slaby if (!(status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS)))
33c6825c63SJeff Brasen break;
347d7dec45SJiri Slaby
357d7dec45SJiri Slaby p->serial_in(p, UART_RX);
367d7dec45SJiri Slaby
37c6825c63SJeff Brasen if (--tmout == 0)
38c6825c63SJeff Brasen break;
39c6825c63SJeff Brasen udelay(1);
407d7dec45SJiri Slaby }
41c6825c63SJeff Brasen }
42c6825c63SJeff Brasen
tegra_uart_probe(struct platform_device * pdev)43c6825c63SJeff Brasen static int tegra_uart_probe(struct platform_device *pdev)
44c6825c63SJeff Brasen {
45c6825c63SJeff Brasen struct uart_8250_port port8250;
46c6825c63SJeff Brasen struct tegra_uart *uart;
47c6825c63SJeff Brasen struct uart_port *port;
48c6825c63SJeff Brasen struct resource *res;
49c6825c63SJeff Brasen int ret;
50c6825c63SJeff Brasen
51c6825c63SJeff Brasen uart = devm_kzalloc(&pdev->dev, sizeof(*uart), GFP_KERNEL);
52c6825c63SJeff Brasen if (!uart)
53c6825c63SJeff Brasen return -ENOMEM;
54c6825c63SJeff Brasen
55c6825c63SJeff Brasen memset(&port8250, 0, sizeof(port8250));
56c6825c63SJeff Brasen
57c6825c63SJeff Brasen port = &port8250.port;
58c6825c63SJeff Brasen spin_lock_init(&port->lock);
59c6825c63SJeff Brasen
60*266bc29dSAndy Shevchenko port->flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_FIXED_TYPE;
61c6825c63SJeff Brasen port->type = PORT_TEGRA;
62c6825c63SJeff Brasen port->dev = &pdev->dev;
63c6825c63SJeff Brasen port->handle_break = tegra_uart_handle_break;
64c6825c63SJeff Brasen
65c6825c63SJeff Brasen res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
66c6825c63SJeff Brasen if (!res)
67c6825c63SJeff Brasen return -ENODEV;
68c6825c63SJeff Brasen
69c6825c63SJeff Brasen port->membase = devm_ioremap(&pdev->dev, res->start,
70c6825c63SJeff Brasen resource_size(res));
71c6825c63SJeff Brasen if (!port->membase)
72c6825c63SJeff Brasen return -ENOMEM;
73c6825c63SJeff Brasen
74c6825c63SJeff Brasen port->mapbase = res->start;
75c6825c63SJeff Brasen port->mapsize = resource_size(res);
76c6825c63SJeff Brasen
77*266bc29dSAndy Shevchenko ret = uart_read_port_properties(port);
78*266bc29dSAndy Shevchenko if (ret)
79*266bc29dSAndy Shevchenko return ret;
80*266bc29dSAndy Shevchenko
81*266bc29dSAndy Shevchenko port->iotype = UPIO_MEM32;
82*266bc29dSAndy Shevchenko port->regshift = 2;
83*266bc29dSAndy Shevchenko
84c6825c63SJeff Brasen uart->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
85c6825c63SJeff Brasen if (IS_ERR(uart->rst))
86c6825c63SJeff Brasen return PTR_ERR(uart->rst);
87c6825c63SJeff Brasen
88*266bc29dSAndy Shevchenko if (!port->uartclk) {
89c6825c63SJeff Brasen uart->clk = devm_clk_get(&pdev->dev, NULL);
90c6825c63SJeff Brasen if (IS_ERR(uart->clk)) {
91c6825c63SJeff Brasen dev_err(&pdev->dev, "failed to get clock!\n");
92c6825c63SJeff Brasen return -ENODEV;
93c6825c63SJeff Brasen }
94c6825c63SJeff Brasen
95c6825c63SJeff Brasen ret = clk_prepare_enable(uart->clk);
96c6825c63SJeff Brasen if (ret < 0)
97c6825c63SJeff Brasen return ret;
98c6825c63SJeff Brasen
99c6825c63SJeff Brasen port->uartclk = clk_get_rate(uart->clk);
100c6825c63SJeff Brasen }
101c6825c63SJeff Brasen
102c6825c63SJeff Brasen ret = reset_control_deassert(uart->rst);
103c6825c63SJeff Brasen if (ret)
104c6825c63SJeff Brasen goto err_clkdisable;
105c6825c63SJeff Brasen
106c6825c63SJeff Brasen ret = serial8250_register_8250_port(&port8250);
107c6825c63SJeff Brasen if (ret < 0)
108134f49deSChristophe JAILLET goto err_ctrl_assert;
109c6825c63SJeff Brasen
110c6825c63SJeff Brasen platform_set_drvdata(pdev, uart);
111c6825c63SJeff Brasen uart->line = ret;
112c6825c63SJeff Brasen
113c6825c63SJeff Brasen return 0;
114c6825c63SJeff Brasen
115134f49deSChristophe JAILLET err_ctrl_assert:
116134f49deSChristophe JAILLET reset_control_assert(uart->rst);
117c6825c63SJeff Brasen err_clkdisable:
118c6825c63SJeff Brasen clk_disable_unprepare(uart->clk);
119c6825c63SJeff Brasen
120c6825c63SJeff Brasen return ret;
121c6825c63SJeff Brasen }
122c6825c63SJeff Brasen
tegra_uart_remove(struct platform_device * pdev)1237e1efdf8SUwe Kleine-König static void tegra_uart_remove(struct platform_device *pdev)
124c6825c63SJeff Brasen {
125c6825c63SJeff Brasen struct tegra_uart *uart = platform_get_drvdata(pdev);
126c6825c63SJeff Brasen
127c6825c63SJeff Brasen serial8250_unregister_port(uart->line);
128c6825c63SJeff Brasen reset_control_assert(uart->rst);
129c6825c63SJeff Brasen clk_disable_unprepare(uart->clk);
130c6825c63SJeff Brasen }
131c6825c63SJeff Brasen
132c6825c63SJeff Brasen #ifdef CONFIG_PM_SLEEP
tegra_uart_suspend(struct device * dev)133c6825c63SJeff Brasen static int tegra_uart_suspend(struct device *dev)
134c6825c63SJeff Brasen {
135c6825c63SJeff Brasen struct tegra_uart *uart = dev_get_drvdata(dev);
136c6825c63SJeff Brasen struct uart_8250_port *port8250 = serial8250_get_port(uart->line);
137c6825c63SJeff Brasen struct uart_port *port = &port8250->port;
138c6825c63SJeff Brasen
139c6825c63SJeff Brasen serial8250_suspend_port(uart->line);
140c6825c63SJeff Brasen
141c6825c63SJeff Brasen if (!uart_console(port) || console_suspend_enabled)
142c6825c63SJeff Brasen clk_disable_unprepare(uart->clk);
143c6825c63SJeff Brasen
144c6825c63SJeff Brasen return 0;
145c6825c63SJeff Brasen }
146c6825c63SJeff Brasen
tegra_uart_resume(struct device * dev)147c6825c63SJeff Brasen static int tegra_uart_resume(struct device *dev)
148c6825c63SJeff Brasen {
149c6825c63SJeff Brasen struct tegra_uart *uart = dev_get_drvdata(dev);
150c6825c63SJeff Brasen struct uart_8250_port *port8250 = serial8250_get_port(uart->line);
151c6825c63SJeff Brasen struct uart_port *port = &port8250->port;
152c6825c63SJeff Brasen
153c6825c63SJeff Brasen if (!uart_console(port) || console_suspend_enabled)
154c6825c63SJeff Brasen clk_prepare_enable(uart->clk);
155c6825c63SJeff Brasen
156c6825c63SJeff Brasen serial8250_resume_port(uart->line);
157c6825c63SJeff Brasen
158c6825c63SJeff Brasen return 0;
159c6825c63SJeff Brasen }
160c6825c63SJeff Brasen #endif
161c6825c63SJeff Brasen
162c6825c63SJeff Brasen static SIMPLE_DEV_PM_OPS(tegra_uart_pm_ops, tegra_uart_suspend,
163c6825c63SJeff Brasen tegra_uart_resume);
164c6825c63SJeff Brasen
165c6825c63SJeff Brasen static const struct of_device_id tegra_uart_of_match[] = {
166c6825c63SJeff Brasen { .compatible = "nvidia,tegra20-uart", },
167c6825c63SJeff Brasen { },
168c6825c63SJeff Brasen };
169c6825c63SJeff Brasen MODULE_DEVICE_TABLE(of, tegra_uart_of_match);
170c6825c63SJeff Brasen
171dffa58b6SKrzysztof Kozlowski static const struct acpi_device_id tegra_uart_acpi_match[] __maybe_unused = {
172c6825c63SJeff Brasen { "NVDA0100", 0 },
173c6825c63SJeff Brasen { },
174c6825c63SJeff Brasen };
175c6825c63SJeff Brasen MODULE_DEVICE_TABLE(acpi, tegra_uart_acpi_match);
176c6825c63SJeff Brasen
177c6825c63SJeff Brasen static struct platform_driver tegra_uart_driver = {
178c6825c63SJeff Brasen .driver = {
179c6825c63SJeff Brasen .name = "tegra-uart",
180c6825c63SJeff Brasen .pm = &tegra_uart_pm_ops,
181c6825c63SJeff Brasen .of_match_table = tegra_uart_of_match,
182c6825c63SJeff Brasen .acpi_match_table = ACPI_PTR(tegra_uart_acpi_match),
183c6825c63SJeff Brasen },
184c6825c63SJeff Brasen .probe = tegra_uart_probe,
1857e1efdf8SUwe Kleine-König .remove_new = tegra_uart_remove,
186c6825c63SJeff Brasen };
187c6825c63SJeff Brasen
188c6825c63SJeff Brasen module_platform_driver(tegra_uart_driver);
189c6825c63SJeff Brasen
190c6825c63SJeff Brasen MODULE_AUTHOR("Jeff Brasen <jbrasen@nvidia.com>");
191c6825c63SJeff Brasen MODULE_DESCRIPTION("NVIDIA Tegra 8250 Driver");
192c6825c63SJeff Brasen MODULE_LICENSE("GPL v2");
193