drivers/mfd/atmel-flexcom.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Driver for Atmel Flexcom
   4  *
   5  * Copyright (C) 2015 Atmel Corporation
   6  *
   7  * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/types.h>
  12 #include <linux/kernel.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/of.h>
  15 #include <linux/of_platform.h>
  16 #include <linux/err.h>
  17 #include <linux/io.h>
  18 #include <linux/clk.h>
  19 #include <dt-bindings/mfd/atmel-flexcom.h>
  20
  21 /* I/O register offsets */
  22 #define FLEX_MR         0x0     /* Mode Register */
  23 #define FLEX_VERSION    0xfc    /* Version Register */
  24
  25 /* Mode Register bit fields */
  26 #define FLEX_MR_OPMODE_OFFSET   (0)  /* Operating Mode */
  27 #define FLEX_MR_OPMODE_MASK     (0x3 << FLEX_MR_OPMODE_OFFSET)
  28 #define FLEX_MR_OPMODE(opmode)  (((opmode) << FLEX_MR_OPMODE_OFFSET) &  \
  29                                  FLEX_MR_OPMODE_MASK)
  30
  31 struct atmel_flexcom {
  32         void __iomem *base;
  33         u32 opmode;
  34         struct clk *clk;
  35 };
  36
  37 static int atmel_flexcom_probe(struct platform_device *pdev)
  38 {
  39         struct device_node *np = pdev->dev.of_node;
  40         struct atmel_flexcom *ddata;
  41         int err;
  42
  43         ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
  44         if (!ddata)
  45                 return -ENOMEM;
  46
  47         platform_set_drvdata(pdev, ddata);
  48
  49         err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
  50         if (err)
  51                 return err;
  52
  53         if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
  54             ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
  55                 return -EINVAL;
  56
  57         ddata->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
  58         if (IS_ERR(ddata->base))
  59                 return PTR_ERR(ddata->base);
  60
  61         ddata->clk = devm_clk_get(&pdev->dev, NULL);
  62         if (IS_ERR(ddata->clk))
  63                 return PTR_ERR(ddata->clk);
  64
  65         err = clk_prepare_enable(ddata->clk);
  66         if (err)
  67                 return err;
  68
  69         /*
  70          * Set the Operating Mode in the Mode Register: only the selected device
  71          * is clocked. Hence, registers of the other serial devices remain
  72          * inaccessible and are read as zero. Also the external I/O lines of the
  73          * Flexcom are muxed to reach the selected device.
  74          */
  75         writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
  76
  77         clk_disable_unprepare(ddata->clk);
  78
  79         return devm_of_platform_populate(&pdev->dev);
  80 }
  81
  82 static const struct of_device_id atmel_flexcom_of_match[] = {
  83         { .compatible = "atmel,sama5d2-flexcom" },
  84         { /* sentinel */ }
  85 };
  86 MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
  87
  88 static int __maybe_unused atmel_flexcom_resume_noirq(struct device *dev)
  89 {
  90         struct atmel_flexcom *ddata = dev_get_drvdata(dev);
  91         int err;
  92         u32 val;
  93
  94         err = clk_prepare_enable(ddata->clk);
  95         if (err)
  96                 return err;
  97
  98         val = FLEX_MR_OPMODE(ddata->opmode);
  99         writel(val, ddata->base + FLEX_MR);
 100
 101         clk_disable_unprepare(ddata->clk);
 102
 103         return 0;
 104 }
 105
 106 static const struct dev_pm_ops __maybe_unused atmel_flexcom_pm_ops = {
 107         .resume_noirq = atmel_flexcom_resume_noirq,
 108 };
 109
 110 static struct platform_driver atmel_flexcom_driver = {
 111         .probe  = atmel_flexcom_probe,
 112         .driver = {
 113                 .name           = "atmel_flexcom",
 114                 .pm             = pm_ptr(&atmel_flexcom_pm_ops),
 115                 .of_match_table = atmel_flexcom_of_match,
 116         },
 117 };
 118
 119 module_platform_driver(atmel_flexcom_driver);
 120
 121 MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
 122 MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
 123 MODULE_LICENSE("GPL v2");