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Commit e8924005 authored by Fabrice Gasnier's avatar Fabrice Gasnier Committed by Lee Jones
Browse files

mfd: Add STM32 LPTimer driver 



STM32 Low-Power Timer hardware block can be used for:
- PWM generation
- IIO trigger (in sync with PWM)
- IIO quadrature encoder counter
PWM and IIO timer configuration are mixed in the same registers so
we need a multi fonction driver to be able to share those registers.

Signed-off-by: default avatarFabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent a7a0db07

drivers/mfd/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -1723,6 +1723,20 @@ config MFD_STW481X 
	  in various ST Microelectronics and ST-Ericsson embedded

	  Nomadik series.



config MFD_STM32_LPTIMER

	tristate "Support for STM32 Low-Power Timer"

	depends on (ARCH_STM32 && OF) || COMPILE_TEST

	select MFD_CORE

	select REGMAP

	select REGMAP_MMIO

	help

	  Select this option to enable STM32 Low-Power Timer driver

	  used for PWM, IIO Trigger, IIO Encoder and Counter. Shared

	  resources are also dealt with here.



	  To compile this driver as a module, choose M here: the

	  module will be called stm32-lptimer.



config MFD_STM32_TIMERS

	tristate "Support for STM32 Timers"

	depends on (ARCH_STM32 && OF) || COMPILE_TEST

drivers/mfd/Makefile

+1 −0
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@@ -221,5 +221,6 @@ obj-$(CONFIG_MFD_MT6397) += mt6397-core.o 
obj-$(CONFIG_MFD_ALTERA_A10SR)	+= altera-a10sr.o

obj-$(CONFIG_MFD_SUN4I_GPADC)	+= sun4i-gpadc.o



obj-$(CONFIG_MFD_STM32_LPTIMER)	+= stm32-lptimer.o

obj-$(CONFIG_MFD_STM32_TIMERS) 	+= stm32-timers.o

obj-$(CONFIG_MFD_MXS_LRADC)     += mxs-lradc.o

drivers/mfd/stm32-lptimer.c

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+107 −0
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/*

 * STM32 Low-Power Timer parent driver.

 *

 * Copyright (C) STMicroelectronics 2017

 *

 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>

 *

 * Inspired by Benjamin Gaignard's stm32-timers driver

 *

 * License terms:  GNU General Public License (GPL), version 2

 */



#include <linux/mfd/stm32-lptimer.h>

#include <linux/module.h>

#include <linux/of_platform.h>



#define STM32_LPTIM_MAX_REGISTER	0x3fc



static const struct regmap_config stm32_lptimer_regmap_cfg = {

	.reg_bits = 32,

	.val_bits = 32,

	.reg_stride = sizeof(u32),

	.max_register = STM32_LPTIM_MAX_REGISTER,

};



static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)

{

	u32 val;

	int ret;



	/*

	 * Quadrature encoder mode bit can only be written and read back when

	 * Low-Power Timer supports it.

	 */

	ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,

				 STM32_LPTIM_ENC, STM32_LPTIM_ENC);

	if (ret)

		return ret;



	ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);

	if (ret)

		return ret;



	ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,

				 STM32_LPTIM_ENC, 0);

	if (ret)

		return ret;



	ddata->has_encoder = !!(val & STM32_LPTIM_ENC);



	return 0;

}



static int stm32_lptimer_probe(struct platform_device *pdev)

{

	struct device *dev = &pdev->dev;

	struct stm32_lptimer *ddata;

	struct resource *res;

	void __iomem *mmio;

	int ret;



	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);

	if (!ddata)

		return -ENOMEM;



	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	mmio = devm_ioremap_resource(dev, res);

	if (IS_ERR(mmio))

		return PTR_ERR(mmio);



	ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio,

						  &stm32_lptimer_regmap_cfg);

	if (IS_ERR(ddata->regmap))

		return PTR_ERR(ddata->regmap);



	ddata->clk = devm_clk_get(dev, NULL);

	if (IS_ERR(ddata->clk))

		return PTR_ERR(ddata->clk);



	ret = stm32_lptimer_detect_encoder(ddata);

	if (ret)

		return ret;



	platform_set_drvdata(pdev, ddata);



	return devm_of_platform_populate(&pdev->dev);

}



static const struct of_device_id stm32_lptimer_of_match[] = {

	{ .compatible = "st,stm32-lptimer", },

	{},

};

MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);



static struct platform_driver stm32_lptimer_driver = {

	.probe = stm32_lptimer_probe,

	.driver = {

		.name = "stm32-lptimer",

		.of_match_table = stm32_lptimer_of_match,

	},

};

module_platform_driver(stm32_lptimer_driver);



MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");

MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");

MODULE_ALIAS("platform:stm32-lptimer");

MODULE_LICENSE("GPL v2");

include/linux/mfd/stm32-lptimer.h

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/*

 * STM32 Low-Power Timer parent driver.

 *

 * Copyright (C) STMicroelectronics 2017

 *

 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>

 *

 * Inspired by Benjamin Gaignard's stm32-timers driver

 *

 * License terms:  GNU General Public License (GPL), version 2

 */



#ifndef _LINUX_STM32_LPTIMER_H_

#define _LINUX_STM32_LPTIMER_H_



#include <linux/clk.h>

#include <linux/regmap.h>



#define STM32_LPTIM_ISR		0x00	/* Interrupt and Status Reg  */

#define STM32_LPTIM_ICR		0x04	/* Interrupt Clear Reg       */

#define STM32_LPTIM_IER		0x08	/* Interrupt Enable Reg      */

#define STM32_LPTIM_CFGR	0x0C	/* Configuration Reg         */

#define STM32_LPTIM_CR		0x10	/* Control Reg               */

#define STM32_LPTIM_CMP		0x14	/* Compare Reg               */

#define STM32_LPTIM_ARR		0x18	/* Autoreload Reg            */

#define STM32_LPTIM_CNT		0x1C	/* Counter Reg               */



/* STM32_LPTIM_ISR - bit fields */

#define STM32_LPTIM_CMPOK_ARROK		GENMASK(4, 3)

#define STM32_LPTIM_ARROK		BIT(4)

#define STM32_LPTIM_CMPOK		BIT(3)



/* STM32_LPTIM_ICR - bit fields */

#define STM32_LPTIM_CMPOKCF_ARROKCF	GENMASK(4, 3)



/* STM32_LPTIM_CR - bit fields */

#define STM32_LPTIM_CNTSTRT	BIT(2)

#define STM32_LPTIM_ENABLE	BIT(0)



/* STM32_LPTIM_CFGR - bit fields */

#define STM32_LPTIM_ENC		BIT(24)

#define STM32_LPTIM_COUNTMODE	BIT(23)

#define STM32_LPTIM_WAVPOL	BIT(21)

#define STM32_LPTIM_PRESC	GENMASK(11, 9)

#define STM32_LPTIM_CKPOL	GENMASK(2, 1)



/* STM32_LPTIM_ARR */

#define STM32_LPTIM_MAX_ARR	0xFFFF



/**

 * struct stm32_lptimer - STM32 Low-Power Timer data assigned by parent device

 * @clk: clock reference for this instance

 * @regmap: register map reference for this instance

 * @has_encoder: indicates this Low-Power Timer supports encoder mode

 */

struct stm32_lptimer {

	struct clk *clk;

	struct regmap *regmap;

	bool has_encoder;

};



#endif