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 
24 struct power_off_cfg {
25 	u32 baud;
26 	char cmd;
27 };
28 
29 static const struct power_off_cfg qnap_power_off_cfg = {
30 	.baud = 19200,
31 	.cmd = 'A',
32 };
33 
34 static const struct power_off_cfg synology_power_off_cfg = {
35 	.baud = 9600,
36 	.cmd = '1',
37 };
38 
39 static 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 };
48 MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
49 
50 static void __iomem *base;
51 static unsigned long tclk;
52 static const struct power_off_cfg *cfg;
53 
54 static 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 
73 static 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 
118 static int qnap_power_off_remove(struct platform_device *pdev)
119 {
120 	pm_power_off = NULL;
121 	return 0;
122 }
123 
124 static 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 };
132 module_platform_driver(qnap_power_off_driver);
133 
134 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
135 MODULE_DESCRIPTION("QNAP Power off driver");
136 MODULE_LICENSE("GPL v2");
137