Eric Lee / smarc-fsl-linux-kernel

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drivers/mfd/stm32-lptimer.c 2.46 KB
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fa93f5b7a   Benjamin Gaignard   mfd: stm32: Adopt... 
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  // SPDX-License-Identifier: GPL-2.0
e8924005b   Fabrice Gasnier   mfd: Add STM32 LP... 
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  /*
   * STM32 Low-Power Timer parent driver.
e8924005b   Fabrice Gasnier   mfd: Add STM32 LP... 
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   * Copyright (C) STMicroelectronics 2017
e8924005b   Fabrice Gasnier   mfd: Add STM32 LP... 
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   * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
e8924005b   Fabrice Gasnier   mfd: Add STM32 LP... 
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   * Inspired by Benjamin Gaignard's stm32-timers driver
e8924005b   Fabrice Gasnier   mfd: Add STM32 LP... 
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   */
  
  #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");