[PATCH 2/8] mfd: Add STM32 LPTimer driver
Lee Jones
lee.jones at linaro.org
Mon Jun 19 08:51:06 PDT 2017
On Fri, 16 Jun 2017, Fabrice Gasnier wrote:
> 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 at st.com>
> ---
> drivers/mfd/Kconfig | 15 ++++++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/stm32-lptimer.c | 110 ++++++++++++++++++++++++++++++++++++++
> include/linux/mfd/stm32-lptimer.h | 55 +++++++++++++++++++
> 4 files changed, 181 insertions(+)
> create mode 100644 drivers/mfd/stm32-lptimer.c
> create mode 100644 include/linux/mfd/stm32-lptimer.h
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 3eb5c93..32c1f3f 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1683,6 +1683,21 @@ config MFD_STW481X
> in various ST Microelectronics and ST-Ericsson embedded
> Nomadik series.
>
> +config MFD_STM32_LPTIMER
> + tristate "Support for STM32 low power timer"
It think this should be "Low Power Timer" throughout.
Or even "Low-Power Timer". You decide.
> + depends on (ARCH_STM32 && OF) || COMPILE_TEST
> + select MFD_CORE
> + select REGMAP
> + select REGMAP_MMIO
> + select RESET_CONTROLLER
> + help
> + Select this option to enable STM32 low power timer driver
> + used for PWM, IIO trigger, IIO encoder and counter. This driver
"Counter"
> + allows to share the resources between these drivers.
"Shared resources are also dealt with here." Or similar.
> + 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
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index c16bf1e..a5308d8 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -219,5 +219,6 @@ 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
> diff --git a/drivers/mfd/stm32-lptimer.c b/drivers/mfd/stm32-lptimer.c
> new file mode 100644
> index 0000000..fcfefa3
> --- /dev/null
> +++ b/drivers/mfd/stm32-lptimer.c
> @@ -0,0 +1,110 @@
> +/*
> + * This file is part of STM32 low-power timer driver
This is a separate driver. It isn't part of anything.
"STM32 Low Power Timer parent driver".
> + * Copyright (C) STMicroelectronics 2017
> + *
> + * Author: Fabrice Gasnier <fabrice.gasnier at st.com>
'\n' here.
> + * Inspired from: stm32-timers from Benjamin Gaignard
"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>
> +#include <linux/reset.h>
> +
> +static const struct regmap_config stm32_lptimer_regmap_cfg = {
> + .reg_bits = 32,
> + .val_bits = 32,
> + .reg_stride = sizeof(u32),
> + .max_register = 0x3fc,
This should be defined.
> +};
> +
> +static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
> +{
> + u32 val, enc = STM32_LPTIM_ENC;
Why have enc? Why not just use STM32_LPTIM_ENC?
> + int ret;
> +
> + /*
> + * Quadrature encoder mode bit can only be written and read back when
> + * LP Timer supports is.
"it"
> + */
> + ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR, enc, enc);
> + if (ret)
> + return ret;
'\n' here.
> + ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
> + if (ret)
> + return ret;
'\n' here.
> + ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR, enc, 0);
> + if (ret)
> + return ret;
'\n' here.
> + ddata->has_encoder = !!val;
> +
> + return 0;
> +}
> +
> +static int stm32_lptimer_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct stm32_lptimer *ddata;
> + struct reset_control *rst;
This looks quite a lot like 'ret'. Just use 'reset'.
> + 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, "int", mmio,
Is that what the clock is called in the datasheet?
> + &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);
> +
> + rst = devm_reset_control_get_optional(dev, NULL);
> + if (IS_ERR(rst))
> + return PTR_ERR(rst);
> +
> + if (rst) {
> + reset_control_assert(rst);
> + reset_control_deassert(rst);
> + }
This is odd. Please provide a comment as to why you're doing this.
> + 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", },
> + { /* end node */ },
No need for the comment.
> +};
> +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 at st.com>");
> +MODULE_DESCRIPTION("STMicroelectronics STM32 Low Power Timer");
> +MODULE_ALIAS("platform:stm32-lptimer");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/mfd/stm32-lptimer.h b/include/linux/mfd/stm32-lptimer.h
> new file mode 100644
> index 0000000..72bc9be
> --- /dev/null
> +++ b/include/linux/mfd/stm32-lptimer.h
> @@ -0,0 +1,55 @@
> +/*
> + * This file is part of STM32 low-power timer driver
> + *
> + * Copyright (C) STMicroelectronics 2016
> + *
> + * Author: Fabrice Gasnier <fabrice.gasnier at st.com>
> + * Inspired from: stm32-timers
Same as the comments I provided for the *.c file above.
> + * 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 {
> + struct clk *clk;
> + struct regmap *regmap;
> + bool has_encoder;
> +};
Please provide a kerneldoc type header for this struct.
> +#endif
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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