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1// SPDX-License-Identifier: GPL-2.0-or-later2/*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_new = 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");132