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Linux/drivers/power/reset/qnap-poweroff.c

  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 
 28 struct power_off_cfg {
 29         u32 baud;
 30         char cmd;
 31 };
 32 
 33 static const struct power_off_cfg qnap_power_off_cfg = {
 34         .baud = 19200,
 35         .cmd = 'A',
 36 };
 37 
 38 static const struct power_off_cfg synology_power_off_cfg = {
 39         .baud = 9600,
 40         .cmd = '1',
 41 };
 42 
 43 static 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 };
 52 MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
 53 
 54 static void __iomem *base;
 55 static unsigned long tclk;
 56 static const struct power_off_cfg *cfg;
 57 
 58 static 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 
 77 static 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 
122 static int qnap_power_off_remove(struct platform_device *pdev)
123 {
124         pm_power_off = NULL;
125         return 0;
126 }
127 
128 static struct platform_driver qnap_power_off_driver = {
129         .probe  = qnap_power_off_probe,
130         .remove = qnap_power_off_remove,
131         .driver = {
132                 .owner  = THIS_MODULE,
133                 .name   = "qnap_power_off",
134                 .of_match_table = of_match_ptr(qnap_power_off_of_match_table),
135         },
136 };
137 module_platform_driver(qnap_power_off_driver);
138 
139 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
140 MODULE_DESCRIPTION("QNAP Power off driver");
141 MODULE_LICENSE("GPL v2");
142 

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