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>

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 94ad2c1..fe76db9 100644 (file)
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -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

diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 080793b..b80b1a3 100644 (file)
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -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

diff --git a/drivers/mfd/stm32-lptimer.c b/drivers/mfd/stm32-lptimer.c
new file mode 100644 (file)
index 0000000..075330a
--- /dev/null
+++ b/drivers/mfd/stm32-lptimer.c
@@ -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");

diff --git a/include/linux/mfd/stm32-lptimer.h b/include/linux/mfd/stm32-lptimer.h
new file mode 100644 (file)
index 0000000..77c7cf4
--- /dev/null
+++ b/include/linux/mfd/stm32-lptimer.h
@@ -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