drivers/mfd/stm32-lptimer.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * STM32 Low-Power Timer parent driver.
0004  * Copyright (C) STMicroelectronics 2017
0005  * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
0006  * Inspired by Benjamin Gaignard's stm32-timers driver
0007  */
0008
0009 #include <linux/mfd/stm32-lptimer.h>
0010 #include <linux/module.h>
0011 #include <linux/of_platform.h>
0012
0013 #define STM32_LPTIM_MAX_REGISTER    0x3fc
0014
0015 static const struct regmap_config stm32_lptimer_regmap_cfg = {
0016     .reg_bits = 32,
0017     .val_bits = 32,
0018     .reg_stride = sizeof(u32),
0019     .max_register = STM32_LPTIM_MAX_REGISTER,
0020     .fast_io = true,
0021 };
0022
0023 static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
0024 {
0025     u32 val;
0026     int ret;
0027
0028     /*
0029      * Quadrature encoder mode bit can only be written and read back when
0030      * Low-Power Timer supports it.
0031      */
0032     ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
0033                  STM32_LPTIM_ENC, STM32_LPTIM_ENC);
0034     if (ret)
0035         return ret;
0036
0037     ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
0038     if (ret)
0039         return ret;
0040
0041     ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
0042                  STM32_LPTIM_ENC, 0);
0043     if (ret)
0044         return ret;
0045
0046     ddata->has_encoder = !!(val & STM32_LPTIM_ENC);
0047
0048     return 0;
0049 }
0050
0051 static int stm32_lptimer_probe(struct platform_device *pdev)
0052 {
0053     struct device *dev = &pdev->dev;
0054     struct stm32_lptimer *ddata;
0055     struct resource *res;
0056     void __iomem *mmio;
0057     int ret;
0058
0059     ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
0060     if (!ddata)
0061         return -ENOMEM;
0062
0063     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
0064     mmio = devm_ioremap_resource(dev, res);
0065     if (IS_ERR(mmio))
0066         return PTR_ERR(mmio);
0067
0068     ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio,
0069                           &stm32_lptimer_regmap_cfg);
0070     if (IS_ERR(ddata->regmap))
0071         return PTR_ERR(ddata->regmap);
0072
0073     ddata->clk = devm_clk_get(dev, NULL);
0074     if (IS_ERR(ddata->clk))
0075         return PTR_ERR(ddata->clk);
0076
0077     ret = stm32_lptimer_detect_encoder(ddata);
0078     if (ret)
0079         return ret;
0080
0081     platform_set_drvdata(pdev, ddata);
0082
0083     return devm_of_platform_populate(&pdev->dev);
0084 }
0085
0086 static const struct of_device_id stm32_lptimer_of_match[] = {
0087     { .compatible = "st,stm32-lptimer", },
0088     {},
0089 };
0090 MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);
0091
0092 static struct platform_driver stm32_lptimer_driver = {
0093     .probe = stm32_lptimer_probe,
0094     .driver = {
0095         .name = "stm32-lptimer",
0096         .of_match_table = stm32_lptimer_of_match,
0097     },
0098 };
0099 module_platform_driver(stm32_lptimer_driver);
0100
0101 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
0102 MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
0103 MODULE_ALIAS("platform:stm32-lptimer");
0104 MODULE_LICENSE("GPL v2");