1 /* 2 * STM32 Low-Power Timer parent driver. 3 * 4 * Copyright (C) STMicroelectronics 2017 5 * 6 * Author: Fabrice Gasnier <fabrice.gasnier@st.com> 7 * 8 * Inspired by Benjamin Gaignard's stm32-timers driver 9 * 10 * License terms: GNU General Public License (GPL), version 2 11 */ 12 13 #include <linux/mfd/stm32-lptimer.h> 14 #include <linux/module.h> 15 #include <linux/of_platform.h> 16 17 #define STM32_LPTIM_MAX_REGISTER 0x3fc 18 19 static const struct regmap_config stm32_lptimer_regmap_cfg = { 20 .reg_bits = 32, 21 .val_bits = 32, 22 .reg_stride = sizeof(u32), 23 .max_register = STM32_LPTIM_MAX_REGISTER, 24 }; 25 26 static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata) 27 { 28 u32 val; 29 int ret; 30 31 /* 32 * Quadrature encoder mode bit can only be written and read back when 33 * Low-Power Timer supports it. 34 */ 35 ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR, 36 STM32_LPTIM_ENC, STM32_LPTIM_ENC); 37 if (ret) 38 return ret; 39 40 ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val); 41 if (ret) 42 return ret; 43 44 ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR, 45 STM32_LPTIM_ENC, 0); 46 if (ret) 47 return ret; 48 49 ddata->has_encoder = !!(val & STM32_LPTIM_ENC); 50 51 return 0; 52 } 53 54 static int stm32_lptimer_probe(struct platform_device *pdev) 55 { 56 struct device *dev = &pdev->dev; 57 struct stm32_lptimer *ddata; 58 struct resource *res; 59 void __iomem *mmio; 60 int ret; 61 62 ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL); 63 if (!ddata) 64 return -ENOMEM; 65 66 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 67 mmio = devm_ioremap_resource(dev, res); 68 if (IS_ERR(mmio)) 69 return PTR_ERR(mmio); 70 71 ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio, 72 &stm32_lptimer_regmap_cfg); 73 if (IS_ERR(ddata->regmap)) 74 return PTR_ERR(ddata->regmap); 75 76 ddata->clk = devm_clk_get(dev, NULL); 77 if (IS_ERR(ddata->clk)) 78 return PTR_ERR(ddata->clk); 79 80 ret = stm32_lptimer_detect_encoder(ddata); 81 if (ret) 82 return ret; 83 84 platform_set_drvdata(pdev, ddata); 85 86 return devm_of_platform_populate(&pdev->dev); 87 } 88 89 static const struct of_device_id stm32_lptimer_of_match[] = { 90 { .compatible = "st,stm32-lptimer", }, 91 {}, 92 }; 93 MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match); 94 95 static struct platform_driver stm32_lptimer_driver = { 96 .probe = stm32_lptimer_probe, 97 .driver = { 98 .name = "stm32-lptimer", 99 .of_match_table = stm32_lptimer_of_match, 100 }, 101 }; 102 module_platform_driver(stm32_lptimer_driver); 103 104 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>"); 105 MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer"); 106 MODULE_ALIAS("platform:stm32-lptimer"); 107 MODULE_LICENSE("GPL v2"); 108