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atmel-flexcom.c
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atmel-flexcom.c
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Driver for Atmel Flexcom
*
* Copyright (C) 2015 Atmel Corporation
*
* Author: Cyrille Pitchen <[email protected]>
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <dt-bindings/mfd/atmel-flexcom.h>
/* I/O register offsets */
#define FLEX_MR 0x0 /* Mode Register */
#define FLEX_VERSION 0xfc /* Version Register */
/* Mode Register bit fields */
#define FLEX_MR_OPMODE_OFFSET (0) /* Operating Mode */
#define FLEX_MR_OPMODE_MASK (0x3 << FLEX_MR_OPMODE_OFFSET)
#define FLEX_MR_OPMODE(opmode) (((opmode) << FLEX_MR_OPMODE_OFFSET) & \
FLEX_MR_OPMODE_MASK)
struct atmel_flexcom {
void __iomem *base;
u32 opmode;
struct clk *clk;
};
static int atmel_flexcom_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct resource *res;
struct atmel_flexcom *ddata;
int err;
ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
if (!ddata)
return -ENOMEM;
platform_set_drvdata(pdev, ddata);
err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
if (err)
return err;
if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
return -EINVAL;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
ddata->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(ddata->base))
return PTR_ERR(ddata->base);
ddata->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(ddata->clk))
return PTR_ERR(ddata->clk);
err = clk_prepare_enable(ddata->clk);
if (err)
return err;
/*
* Set the Operating Mode in the Mode Register: only the selected device
* is clocked. Hence, registers of the other serial devices remain
* inaccessible and are read as zero. Also the external I/O lines of the
* Flexcom are muxed to reach the selected device.
*/
writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
clk_disable_unprepare(ddata->clk);
return devm_of_platform_populate(&pdev->dev);
}
static const struct of_device_id atmel_flexcom_of_match[] = {
{ .compatible = "atmel,sama5d2-flexcom" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
#ifdef CONFIG_PM_SLEEP
static int atmel_flexcom_resume(struct device *dev)
{
struct atmel_flexcom *ddata = dev_get_drvdata(dev);
int err;
u32 val;
err = clk_prepare_enable(ddata->clk);
if (err)
return err;
val = FLEX_MR_OPMODE(ddata->opmode),
writel(val, ddata->base + FLEX_MR);
clk_disable_unprepare(ddata->clk);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL,
atmel_flexcom_resume);
static struct platform_driver atmel_flexcom_driver = {
.probe = atmel_flexcom_probe,
.driver = {
.name = "atmel_flexcom",
.pm = &atmel_flexcom_pm_ops,
.of_match_table = atmel_flexcom_of_match,
},
};
module_platform_driver(atmel_flexcom_driver);
MODULE_AUTHOR("Cyrille Pitchen <[email protected]>");
MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
MODULE_LICENSE("GPL v2");