mfd: Add STM32 Timers driver

This hardware block could at used at same time for PWM generation
and IIO timers.
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.

version 7:
- rebase on v4.10-rc2

version 6:
- rename files to stm32-timers
- rename functions to stm32_timers_xxx

version 5:
- fix Lee comments about detect function
- add missing dependency on REGMAP_MMIO

version 4:
- add a function to detect Auto Reload Register (ARR) size
- rename the structure shared with other drivers

version 2:
- rename driver "stm32-gptimer" to be align with SoC documentation
- only keep one compatible
- use of_platform_populate() instead of devm_mfd_add_devices()

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -1621,6 +1621,17 @@ config MFD_STW481X
 	  in various ST Microelectronics and ST-Ericsson embedded
 	  Nomadik series.
 
+config MFD_STM32_TIMERS
+	tristate "Support for STM32 Timers"
+	depends on (ARCH_STM32 && OF) || COMPILE_TEST
+	select MFD_CORE
+	select REGMAP
+	select REGMAP_MMIO
+	help
+	  Select this option to enable STM32 timers driver used
+	  for PWM and IIO Timer. This driver allow to share the
+	  registers between the others drivers.
+
 menu "Multimedia Capabilities Port drivers"
 	depends on ARCH_SA1100
 

drivers/mfd/Makefile

@@ -212,3 +212,5 @@ 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_TIMERS) 	+= stm32-timers.o

drivers/mfd/stm32-timers.c

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) STMicroelectronics 2016
+ *
+ * Author: Benjamin Gaignard <benjamin.gaignard@st.com>
+ *
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#include <linux/mfd/stm32-timers.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/reset.h>
+
+static const struct regmap_config stm32_timers_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = sizeof(u32),
+	.max_register = 0x400,
+};
+
+static void stm32_timers_get_arr_size(struct stm32_timers *ddata)
+{
+	/*
+	 * Only the available bits will be written so when readback
+	 * we get the maximum value of auto reload register
+	 */
+	regmap_write(ddata->regmap, TIM_ARR, ~0L);
+	regmap_read(ddata->regmap, TIM_ARR, &ddata->max_arr);
+	regmap_write(ddata->regmap, TIM_ARR, 0x0);
+}
+
+static int stm32_timers_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct stm32_timers *ddata;
+	struct resource *res;
+	void __iomem *mmio;
+
+	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,
+						  &stm32_timers_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);
+
+	stm32_timers_get_arr_size(ddata);
+
+	platform_set_drvdata(pdev, ddata);
+
+	return of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
+}
+
+static const struct of_device_id stm32_timers_of_match[] = {
+	{ .compatible = "st,stm32-timers", },
+	{ /* end node */ },
+};
+MODULE_DEVICE_TABLE(of, stm32_timers_of_match);
+
+static struct platform_driver stm32_timers_driver = {
+	.probe = stm32_timers_probe,
+	.driver	= {
+		.name = "stm32-timers",
+		.of_match_table = stm32_timers_of_match,
+	},
+};
+module_platform_driver(stm32_timers_driver);
+
+MODULE_DESCRIPTION("STMicroelectronics STM32 Timers");
+MODULE_LICENSE("GPL v2");

include/linux/mfd/stm32-timers.h

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) STMicroelectronics 2016
+ *
+ * Author: Benjamin Gaignard <benjamin.gaignard@st.com>
+ *
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#ifndef _LINUX_STM32_GPTIMER_H_
+#define _LINUX_STM32_GPTIMER_H_
+
+#include <linux/clk.h>
+#include <linux/regmap.h>
+
+#define TIM_CR1		0x00	/* Control Register 1      */
+#define TIM_CR2		0x04	/* Control Register 2      */
+#define TIM_SMCR	0x08	/* Slave mode control reg  */
+#define TIM_DIER	0x0C	/* DMA/interrupt register  */
+#define TIM_SR		0x10	/* Status register	   */
+#define TIM_EGR		0x14	/* Event Generation Reg    */
+#define TIM_CCMR1	0x18	/* Capt/Comp 1 Mode Reg    */
+#define TIM_CCMR2	0x1C	/* Capt/Comp 2 Mode Reg    */
+#define TIM_CCER	0x20	/* Capt/Comp Enable Reg    */
+#define TIM_PSC		0x28	/* Prescaler               */
+#define TIM_ARR		0x2c	/* Auto-Reload Register    */
+#define TIM_CCR1	0x34	/* Capt/Comp Register 1    */
+#define TIM_CCR2	0x38	/* Capt/Comp Register 2    */
+#define TIM_CCR3	0x3C	/* Capt/Comp Register 3    */
+#define TIM_CCR4	0x40	/* Capt/Comp Register 4    */
+#define TIM_BDTR	0x44	/* Break and Dead-Time Reg */
+
+#define TIM_CR1_CEN	BIT(0)	/* Counter Enable	   */
+#define TIM_CR1_ARPE	BIT(7)	/* Auto-reload Preload Ena */
+#define TIM_CR2_MMS	(BIT(4) | BIT(5) | BIT(6)) /* Master mode selection */
+#define TIM_SMCR_SMS	(BIT(0) | BIT(1) | BIT(2)) /* Slave mode selection */
+#define TIM_SMCR_TS	(BIT(4) | BIT(5) | BIT(6)) /* Trigger selection */
+#define TIM_DIER_UIE	BIT(0)	/* Update interrupt	   */
+#define TIM_SR_UIF	BIT(0)	/* Update interrupt flag   */
+#define TIM_EGR_UG	BIT(0)	/* Update Generation       */
+#define TIM_CCMR_PE	BIT(3)	/* Channel Preload Enable  */
+#define TIM_CCMR_M1	(BIT(6) | BIT(5))  /* Channel PWM Mode 1 */
+#define TIM_CCER_CC1E	BIT(0)	/* Capt/Comp 1  out Ena    */
+#define TIM_CCER_CC1P	BIT(1)	/* Capt/Comp 1  Polarity   */
+#define TIM_CCER_CC1NE	BIT(2)	/* Capt/Comp 1N out Ena    */
+#define TIM_CCER_CC1NP	BIT(3)	/* Capt/Comp 1N Polarity   */
+#define TIM_CCER_CC2E	BIT(4)	/* Capt/Comp 2  out Ena    */
+#define TIM_CCER_CC3E	BIT(8)	/* Capt/Comp 3  out Ena    */
+#define TIM_CCER_CC4E	BIT(12)	/* Capt/Comp 4  out Ena    */
+#define TIM_CCER_CCXE	(BIT(0) | BIT(4) | BIT(8) | BIT(12))
+#define TIM_BDTR_BKE	BIT(12) /* Break input enable	   */
+#define TIM_BDTR_BKP	BIT(13) /* Break input polarity	   */
+#define TIM_BDTR_AOE	BIT(14)	/* Automatic Output Enable */
+#define TIM_BDTR_MOE	BIT(15)	/* Main Output Enable      */
+#define TIM_BDTR_BKF	(BIT(16) | BIT(17) | BIT(18) | BIT(19))
+#define TIM_BDTR_BK2F	(BIT(20) | BIT(21) | BIT(22) | BIT(23))
+#define TIM_BDTR_BK2E	BIT(24) /* Break 2 input enable	   */
+#define TIM_BDTR_BK2P	BIT(25) /* Break 2 input polarity  */
+
+#define MAX_TIM_PSC		0xFFFF
+#define TIM_CR2_MMS_SHIFT	4
+#define TIM_SMCR_TS_SHIFT	4
+#define TIM_BDTR_BKF_MASK	0xF
+#define TIM_BDTR_BKF_SHIFT	16
+#define TIM_BDTR_BK2F_SHIFT	20
+
+struct stm32_timers {
+	struct clk *clk;
+	struct regmap *regmap;
+	u32 max_arr;
+};
+#endif