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