1/*
2 * QNAP Turbo NAS Board power off. Can also be used on Synology devices.
3 *
4 * Copyright (C) 2012 Andrew Lunn <andrew@lunn.ch>
5 *
6 * Based on the code from:
7 *
8 * Copyright (C) 2009  Martin Michlmayr <tbm@cyrius.com>
9 * Copyright (C) 2008  Byron Bradley <byron.bbradley@gmail.com>
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 */
16
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/platform_device.h>
20#include <linux/serial_reg.h>
21#include <linux/kallsyms.h>
22#include <linux/of.h>
23#include <linux/io.h>
24#include <linux/clk.h>
25
26#define UART1_REG(x)	(base + ((UART_##x) << 2))
27
28struct power_off_cfg {
29	u32 baud;
30	char cmd;
31};
32
33static const struct power_off_cfg qnap_power_off_cfg = {
34	.baud = 19200,
35	.cmd = 'A',
36};
37
38static const struct power_off_cfg synology_power_off_cfg = {
39	.baud = 9600,
40	.cmd = '1',
41};
42
43static const struct of_device_id qnap_power_off_of_match_table[] = {
44	{ .compatible = "qnap,power-off",
45	  .data = &qnap_power_off_cfg,
46	},
47	{ .compatible = "synology,power-off",
48	  .data = &synology_power_off_cfg,
49	},
50	{}
51};
52MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
53
54static void __iomem *base;
55static unsigned long tclk;
56static const struct power_off_cfg *cfg;
57
58static void qnap_power_off(void)
59{
60	const unsigned divisor = ((tclk + (8 * cfg->baud)) / (16 * cfg->baud));
61
62	pr_err("%s: triggering power-off...\n", __func__);
63
64	/* hijack UART1 and reset into sane state */
65	writel(0x83, UART1_REG(LCR));
66	writel(divisor & 0xff, UART1_REG(DLL));
67	writel((divisor >> 8) & 0xff, UART1_REG(DLM));
68	writel(0x03, UART1_REG(LCR));
69	writel(0x00, UART1_REG(IER));
70	writel(0x00, UART1_REG(FCR));
71	writel(0x00, UART1_REG(MCR));
72
73	/* send the power-off command to PIC */
74	writel(cfg->cmd, UART1_REG(TX));
75}
76
77static int qnap_power_off_probe(struct platform_device *pdev)
78{
79	struct device_node *np = pdev->dev.of_node;
80	struct resource *res;
81	struct clk *clk;
82	char symname[KSYM_NAME_LEN];
83
84	const struct of_device_id *match =
85		of_match_node(qnap_power_off_of_match_table, np);
86	cfg = match->data;
87
88	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
89	if (!res) {
90		dev_err(&pdev->dev, "Missing resource");
91		return -EINVAL;
92	}
93
94	base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
95	if (!base) {
96		dev_err(&pdev->dev, "Unable to map resource");
97		return -EINVAL;
98	}
99
100	/* We need to know tclk in order to calculate the UART divisor */
101	clk = devm_clk_get(&pdev->dev, NULL);
102	if (IS_ERR(clk)) {
103		dev_err(&pdev->dev, "Clk missing");
104		return PTR_ERR(clk);
105	}
106
107	tclk = clk_get_rate(clk);
108
109	/* Check that nothing else has already setup a handler */
110	if (pm_power_off) {
111		lookup_symbol_name((ulong)pm_power_off, symname);
112		dev_err(&pdev->dev,
113			"pm_power_off already claimed %p %s",
114			pm_power_off, symname);
115		return -EBUSY;
116	}
117	pm_power_off = qnap_power_off;
118
119	return 0;
120}
121
122static int qnap_power_off_remove(struct platform_device *pdev)
123{
124	pm_power_off = NULL;
125	return 0;
126}
127
128static struct platform_driver qnap_power_off_driver = {
129	.probe	= qnap_power_off_probe,
130	.remove	= qnap_power_off_remove,
131	.driver	= {
132		.name	= "qnap_power_off",
133		.of_match_table = of_match_ptr(qnap_power_off_of_match_table),
134	},
135};
136module_platform_driver(qnap_power_off_driver);
137
138MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
139MODULE_DESCRIPTION("QNAP Power off driver");
140MODULE_LICENSE("GPL v2");
141