drivers/power/reset/qnap-poweroff.c

   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
  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
  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
 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");