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authorFabrice Gasnier <fabrice.gasnier@st.com>2017-08-28 12:04:07 +0200
committerLee Jones <lee.jones@linaro.org>2017-09-04 14:49:04 +0100
commite8924005b4e7964313536547d4b73406330be26d (patch)
tree39d9d5069fb89b1db3d43678e18e241f295971cc /drivers/mfd/stm32-lptimer.c
parenta7a0db07e9ffd55278b080b0a8e466853075f2c7 (diff)
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>
Diffstat (limited to 'drivers/mfd/stm32-lptimer.c')
-rw-r--r--drivers/mfd/stm32-lptimer.c107
1 files changed, 107 insertions, 0 deletions
diff --git a/drivers/mfd/stm32-lptimer.c b/drivers/mfd/stm32-lptimer.c
new file mode 100644
index 000000000000..075330a25f61
--- /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");