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 resource *res;
  41         struct atmel_flexcom *ddata;
  42         int err;
  43
  44         ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
  45         if (!ddata)
  46                 return -ENOMEM;
  47
  48         platform_set_drvdata(pdev, ddata);
  49
  50         err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
  51         if (err)
  52                 return err;
  53
  54         if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
  55             ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
  56                 return -EINVAL;
  57
  58         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  59         ddata->base = devm_ioremap_resource(&pdev->dev, res);
  60         if (IS_ERR(ddata->base))
  61                 return PTR_ERR(ddata->base);
  62
  63         ddata->clk = devm_clk_get(&pdev->dev, NULL);
  64         if (IS_ERR(ddata->clk))
  65                 return PTR_ERR(ddata->clk);
  66
  67         err = clk_prepare_enable(ddata->clk);
  68         if (err)
  69                 return err;
  70
  71         /*
  72          * Set the Operating Mode in the Mode Register: only the selected device
  73          * is clocked. Hence, registers of the other serial devices remain
  74          * inaccessible and are read as zero. Also the external I/O lines of the
  75          * Flexcom are muxed to reach the selected device.
  76          */
  77         writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
  78
  79         clk_disable_unprepare(ddata->clk);
  80
  81         return devm_of_platform_populate(&pdev->dev);
  82 }
  83
  84 static const struct of_device_id atmel_flexcom_of_match[] = {
  85         { .compatible = "atmel,sama5d2-flexcom" },
  86         { /* sentinel */ }
  87 };
  88 MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
  89
  90 #ifdef CONFIG_PM_SLEEP
  91 static int atmel_flexcom_resume(struct device *dev)
  92 {
  93         struct atmel_flexcom *ddata = dev_get_drvdata(dev);
  94         int err;
  95         u32 val;
  96
  97         err = clk_prepare_enable(ddata->clk);
  98         if (err)
  99                 return err;
 100
 101         val = FLEX_MR_OPMODE(ddata->opmode),
 102         writel(val, ddata->base + FLEX_MR);
 103
 104         clk_disable_unprepare(ddata->clk);
 105
 106         return 0;
 107 }
 108 #endif
 109
 110 static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL,
 111                          atmel_flexcom_resume);
 112
 113 static struct platform_driver atmel_flexcom_driver = {
 114         .probe  = atmel_flexcom_probe,
 115         .driver = {
 116                 .name           = "atmel_flexcom",
 117                 .pm             = &atmel_flexcom_pm_ops,
 118                 .of_match_table = atmel_flexcom_of_match,
 119         },
 120 };
 121
 122 module_platform_driver(atmel_flexcom_driver);
 123
 124 MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
 125 MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
 126 MODULE_LICENSE("GPL v2");