1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * QNAP Turbo NAS Board power off. Can also be used on Synology devices.
4 *
5 * Copyright (C) 2012 Andrew Lunn <andrew@lunn.ch>
6 *
7 * Based on the code from:
8 *
9 * Copyright (C) 2009  Martin Michlmayr <tbm@cyrius.com>
10 * Copyright (C) 2008  Byron Bradley <byron.bbradley@gmail.com>
11 */
12
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/platform_device.h>
16#include <linux/serial_reg.h>
17#include <linux/kallsyms.h>
18#include <linux/of.h>
19#include <linux/io.h>
20#include <linux/clk.h>
21
22#define UART1_REG(x)	(base + ((UART_##x) << 2))
23
24struct power_off_cfg {
25	u32 baud;
26	char cmd;
27};
28
29static const struct power_off_cfg qnap_power_off_cfg = {
30	.baud = 19200,
31	.cmd = 'A',
32};
33
34static const struct power_off_cfg synology_power_off_cfg = {
35	.baud = 9600,
36	.cmd = '1',
37};
38
39static const struct of_device_id qnap_power_off_of_match_table[] = {
40	{ .compatible = "qnap,power-off",
41	  .data = &qnap_power_off_cfg,
42	},
43	{ .compatible = "synology,power-off",
44	  .data = &synology_power_off_cfg,
45	},
46	{}
47};
48MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
49
50static void __iomem *base;
51static unsigned long tclk;
52static const struct power_off_cfg *cfg;
53
54static void qnap_power_off(void)
55{
56	const unsigned divisor = ((tclk + (8 * cfg->baud)) / (16 * cfg->baud));
57
58	pr_err("%s: triggering power-off...\n", __func__);
59
60	/* hijack UART1 and reset into sane state */
61	writel(0x83, UART1_REG(LCR));
62	writel(divisor & 0xff, UART1_REG(DLL));
63	writel((divisor >> 8) & 0xff, UART1_REG(DLM));
64	writel(0x03, UART1_REG(LCR));
65	writel(0x00, UART1_REG(IER));
66	writel(0x00, UART1_REG(FCR));
67	writel(0x00, UART1_REG(MCR));
68
69	/* send the power-off command to PIC */
70	writel(cfg->cmd, UART1_REG(TX));
71}
72
73static int qnap_power_off_probe(struct platform_device *pdev)
74{
75	struct device_node *np = pdev->dev.of_node;
76	struct resource *res;
77	struct clk *clk;
78	char symname[KSYM_NAME_LEN];
79
80	const struct of_device_id *match =
81		of_match_node(qnap_power_off_of_match_table, np);
82	cfg = match->data;
83
84	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
85	if (!res) {
86		dev_err(&pdev->dev, "Missing resource");
87		return -EINVAL;
88	}
89
90	base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
91	if (!base) {
92		dev_err(&pdev->dev, "Unable to map resource");
93		return -EINVAL;
94	}
95
96	/* We need to know tclk in order to calculate the UART divisor */
97	clk = devm_clk_get(&pdev->dev, NULL);
98	if (IS_ERR(clk)) {
99		dev_err(&pdev->dev, "Clk missing");
100		return PTR_ERR(clk);
101	}
102
103	tclk = clk_get_rate(clk);
104
105	/* Check that nothing else has already setup a handler */
106	if (pm_power_off) {
107		lookup_symbol_name((ulong)pm_power_off, symname);
108		dev_err(&pdev->dev,
109			"pm_power_off already claimed %p %s",
110			pm_power_off, symname);
111		return -EBUSY;
112	}
113	pm_power_off = qnap_power_off;
114
115	return 0;
116}
117
118static int qnap_power_off_remove(struct platform_device *pdev)
119{
120	pm_power_off = NULL;
121	return 0;
122}
123
124static struct platform_driver qnap_power_off_driver = {
125	.probe	= qnap_power_off_probe,
126	.remove	= qnap_power_off_remove,
127	.driver	= {
128		.name	= "qnap_power_off",
129		.of_match_table = of_match_ptr(qnap_power_off_of_match_table),
130	},
131};
132module_platform_driver(qnap_power_off_driver);
133
134MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
135MODULE_DESCRIPTION("QNAP Power off driver");
136MODULE_LICENSE("GPL v2");
137