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Subject[PATCH v2 2/8] mfd: Add STM32 LPTimer driver
Date
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>
---
Changes in v2:
- Lee's remarks: various comments, max register define, s/Low Power/Low-Power,
clock name, removed reset, add kernel doc for stm32_lptimer struct
---
drivers/mfd/Kconfig | 14 +++++
drivers/mfd/Makefile | 1 +
drivers/mfd/stm32-lptimer.c | 107 ++++++++++++++++++++++++++++++++++++++
include/linux/mfd/stm32-lptimer.h | 62 ++++++++++++++++++++++
4 files changed, 184 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..8e1ca44 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1683,6 +1683,20 @@ 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 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..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
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
--
1.9.1
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