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
 23struct power_off_cfg {
 24	u32 baud;
 25	char cmd;
 26};
 27
 28static const struct power_off_cfg qnap_power_off_cfg = {
 29	.baud = 19200,
 30	.cmd = 'A',
 31};
 32
 33static const struct power_off_cfg synology_power_off_cfg = {
 34	.baud = 9600,
 35	.cmd = '1',
 36};
 37
 38static 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};
 47MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
 48
 49static void __iomem *base;
 50static unsigned long tclk;
 51static const struct power_off_cfg *cfg;
 52
 53static 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
 72static 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
114static void qnap_power_off_remove(struct platform_device *pdev)
115{
116	pm_power_off = NULL;
117}
118
119static struct platform_driver qnap_power_off_driver = {
120	.probe	= qnap_power_off_probe,
121	.remove	= qnap_power_off_remove,
122	.driver	= {
123		.name	= "qnap_power_off",
124		.of_match_table = of_match_ptr(qnap_power_off_of_match_table),
125	},
126};
127module_platform_driver(qnap_power_off_driver);
128
129MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
130MODULE_DESCRIPTION("QNAP Power off driver");
131MODULE_LICENSE("GPL v2");