1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * STM32 Low-Power Timer parent driver. 4 * Copyright (C) STMicroelectronics 2017 5 * Author: Fabrice Gasnier <fabrice.gasnier@st.com> 6 * Inspired by Benjamin Gaignard's stm32-timers driver 7 */ 8 9 #include <linux/mfd/stm32-lptimer.h> 10 #include <linux/module.h> 11 #include <linux/of_platform.h> 12 #include <linux/platform_device.h> 13 14 #define STM32_LPTIM_MAX_REGISTER 0x3fc 15 16 static const struct regmap_config stm32_lptimer_regmap_cfg = { 17 .reg_bits = 32, 18 .val_bits = 32, 19 .reg_stride = sizeof(u32), 20 .max_register = STM32_LPTIM_MAX_REGISTER, 21 .fast_io = true, 22 }; 23 24 static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata) 25 { 26 u32 val; 27 int ret; 28 29 /* 30 * Quadrature encoder mode bit can only be written and read back when 31 * Low-Power Timer supports it. 32 */ 33 ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR, 34 STM32_LPTIM_ENC, STM32_LPTIM_ENC); 35 if (ret) 36 return ret; 37 38 ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val); 39 if (ret) 40 return ret; 41 42 ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR, 43 STM32_LPTIM_ENC, 0); 44 if (ret) 45 return ret; 46 47 ddata->has_encoder = !!(val & STM32_LPTIM_ENC); 48 49 return 0; 50 } 51 52 static int stm32_lptimer_probe(struct platform_device *pdev) 53 { 54 struct device *dev = &pdev->dev; 55 struct stm32_lptimer *ddata; 56 void __iomem *mmio; 57 int ret; 58 59 ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL); 60 if (!ddata) 61 return -ENOMEM; 62 63 mmio = devm_platform_get_and_ioremap_resource(pdev, 0, NULL); 64 if (IS_ERR(mmio)) 65 return PTR_ERR(mmio); 66 67 ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio, 68 &stm32_lptimer_regmap_cfg); 69 if (IS_ERR(ddata->regmap)) 70 return PTR_ERR(ddata->regmap); 71 72 ddata->clk = devm_clk_get(dev, NULL); 73 if (IS_ERR(ddata->clk)) 74 return PTR_ERR(ddata->clk); 75 76 ret = stm32_lptimer_detect_encoder(ddata); 77 if (ret) 78 return ret; 79 80 platform_set_drvdata(pdev, ddata); 81 82 return devm_of_platform_populate(&pdev->dev); 83 } 84 85 static const struct of_device_id stm32_lptimer_of_match[] = { 86 { .compatible = "st,stm32-lptimer", }, 87 {}, 88 }; 89 MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match); 90 91 static struct platform_driver stm32_lptimer_driver = { 92 .probe = stm32_lptimer_probe, 93 .driver = { 94 .name = "stm32-lptimer", 95 .of_match_table = stm32_lptimer_of_match, 96 }, 97 }; 98 module_platform_driver(stm32_lptimer_driver); 99 100 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>"); 101 MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer"); 102 MODULE_ALIAS("platform:stm32-lptimer"); 103 MODULE_LICENSE("GPL v2"); 104