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: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Fabrice Gasnier 2017-08-28 12:04:07 +02:00 committed by Lee Jones
parent a7a0db07e9
commit e8924005b4
4 changed files with 184 additions and 0 deletions

View File

@ -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

View File

@ -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

107
drivers/mfd/stm32-lptimer.c Normal file
View File

@ -0,0 +1,107 @@
/*
* 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");

View File

@ -0,0 +1,62 @@
/*
* 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