cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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qnap-poweroff.c (3201B)

      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 int qnap_power_off_remove(struct platform_device *pdev)
    115{
    116	pm_power_off = NULL;
    117	return 0;
    118}
    119
    120static 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};
    128module_platform_driver(qnap_power_off_driver);
    129
    130MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
    131MODULE_DESCRIPTION("QNAP Power off driver");
    132MODULE_LICENSE("GPL v2");