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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atmel-flexcom.c (3213B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Driver for Atmel Flexcom
      4 *
      5 * Copyright (C) 2015 Atmel Corporation
      6 *
      7 * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
      8 */
      9
     10#include <linux/module.h>
     11#include <linux/types.h>
     12#include <linux/kernel.h>
     13#include <linux/platform_device.h>
     14#include <linux/of.h>
     15#include <linux/of_platform.h>
     16#include <linux/err.h>
     17#include <linux/io.h>
     18#include <linux/clk.h>
     19#include <dt-bindings/mfd/atmel-flexcom.h>
     20
     21/* I/O register offsets */
     22#define FLEX_MR		0x0	/* Mode Register */
     23#define FLEX_VERSION	0xfc	/* Version Register */
     24
     25/* Mode Register bit fields */
     26#define FLEX_MR_OPMODE_OFFSET	(0)  /* Operating Mode */
     27#define FLEX_MR_OPMODE_MASK	(0x3 << FLEX_MR_OPMODE_OFFSET)
     28#define FLEX_MR_OPMODE(opmode)	(((opmode) << FLEX_MR_OPMODE_OFFSET) &	\
     29				 FLEX_MR_OPMODE_MASK)
     30
     31struct atmel_flexcom {
     32	void __iomem *base;
     33	u32 opmode;
     34	struct clk *clk;
     35};
     36
     37static int atmel_flexcom_probe(struct platform_device *pdev)
     38{
     39	struct device_node *np = pdev->dev.of_node;
     40	struct resource *res;
     41	struct atmel_flexcom *ddata;
     42	int err;
     43
     44	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
     45	if (!ddata)
     46		return -ENOMEM;
     47
     48	platform_set_drvdata(pdev, ddata);
     49
     50	err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
     51	if (err)
     52		return err;
     53
     54	if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
     55	    ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
     56		return -EINVAL;
     57
     58	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
     59	ddata->base = devm_ioremap_resource(&pdev->dev, res);
     60	if (IS_ERR(ddata->base))
     61		return PTR_ERR(ddata->base);
     62
     63	ddata->clk = devm_clk_get(&pdev->dev, NULL);
     64	if (IS_ERR(ddata->clk))
     65		return PTR_ERR(ddata->clk);
     66
     67	err = clk_prepare_enable(ddata->clk);
     68	if (err)
     69		return err;
     70
     71	/*
     72	 * Set the Operating Mode in the Mode Register: only the selected device
     73	 * is clocked. Hence, registers of the other serial devices remain
     74	 * inaccessible and are read as zero. Also the external I/O lines of the
     75	 * Flexcom are muxed to reach the selected device.
     76	 */
     77	writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
     78
     79	clk_disable_unprepare(ddata->clk);
     80
     81	return devm_of_platform_populate(&pdev->dev);
     82}
     83
     84static const struct of_device_id atmel_flexcom_of_match[] = {
     85	{ .compatible = "atmel,sama5d2-flexcom" },
     86	{ /* sentinel */ }
     87};
     88MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
     89
     90static int __maybe_unused atmel_flexcom_resume_noirq(struct device *dev)
     91{
     92	struct atmel_flexcom *ddata = dev_get_drvdata(dev);
     93	int err;
     94	u32 val;
     95
     96	err = clk_prepare_enable(ddata->clk);
     97	if (err)
     98		return err;
     99
    100	val = FLEX_MR_OPMODE(ddata->opmode),
    101	writel(val, ddata->base + FLEX_MR);
    102
    103	clk_disable_unprepare(ddata->clk);
    104
    105	return 0;
    106}
    107
    108static const struct dev_pm_ops __maybe_unused atmel_flexcom_pm_ops = {
    109	.resume_noirq = atmel_flexcom_resume_noirq,
    110};
    111
    112static struct platform_driver atmel_flexcom_driver = {
    113	.probe	= atmel_flexcom_probe,
    114	.driver	= {
    115		.name		= "atmel_flexcom",
    116		.pm		= pm_ptr(&atmel_flexcom_pm_ops),
    117		.of_match_table	= atmel_flexcom_of_match,
    118	},
    119};
    120
    121module_platform_driver(atmel_flexcom_driver);
    122
    123MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
    124MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
    125MODULE_LICENSE("GPL v2");