drivers/mfd/atmel-flexcom.c

   1 /*
   2  * Driver for Atmel Flexcom
   3  *
   4  * Copyright (C) 2015 Atmel Corporation
   5  *
   6  * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15  * more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along with
  18  * this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/types.h>
  23 #include <linux/kernel.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/of.h>
  26 #include <linux/of_platform.h>
  27 #include <linux/err.h>
  28 #include <linux/io.h>
  29 #include <linux/clk.h>
  30 #include <dt-bindings/mfd/atmel-flexcom.h>
  31
  32 /* I/O register offsets */
  33 #define FLEX_MR         0x0     /* Mode Register */
  34 #define FLEX_VERSION    0xfc    /* Version Register */
  35
  36 /* Mode Register bit fields */
  37 #define FLEX_MR_OPMODE_OFFSET   (0)  /* Operating Mode */
  38 #define FLEX_MR_OPMODE_MASK     (0x3 << FLEX_MR_OPMODE_OFFSET)
  39 #define FLEX_MR_OPMODE(opmode)  (((opmode) << FLEX_MR_OPMODE_OFFSET) &  \
  40                                  FLEX_MR_OPMODE_MASK)
  41
  42 struct atmel_flexcom {
  43         void __iomem *base;
  44         u32 opmode;
  45         struct clk *clk;
  46 };
  47
  48 static int atmel_flexcom_probe(struct platform_device *pdev)
  49 {
  50         struct device_node *np = pdev->dev.of_node;
  51         struct resource *res;
  52         struct atmel_flexcom *ddata;
  53         int err;
  54
  55         ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
  56         if (!ddata)
  57                 return -ENOMEM;
  58
  59         platform_set_drvdata(pdev, ddata);
  60
  61         err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
  62         if (err)
  63                 return err;
  64
  65         if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
  66             ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
  67                 return -EINVAL;
  68
  69         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  70         ddata->base = devm_ioremap_resource(&pdev->dev, res);
  71         if (IS_ERR(ddata->base))
  72                 return PTR_ERR(ddata->base);
  73
  74         ddata->clk = devm_clk_get(&pdev->dev, NULL);
  75         if (IS_ERR(ddata->clk))
  76                 return PTR_ERR(ddata->clk);
  77
  78         err = clk_prepare_enable(ddata->clk);
  79         if (err)
  80                 return err;
  81
  82         /*
  83          * Set the Operating Mode in the Mode Register: only the selected device
  84          * is clocked. Hence, registers of the other serial devices remain
  85          * inaccessible and are read as zero. Also the external I/O lines of the
  86          * Flexcom are muxed to reach the selected device.
  87          */
  88         writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
  89
  90         clk_disable_unprepare(ddata->clk);
  91
  92         return devm_of_platform_populate(&pdev->dev);
  93 }
  94
  95 static const struct of_device_id atmel_flexcom_of_match[] = {
  96         { .compatible = "atmel,sama5d2-flexcom" },
  97         { /* sentinel */ }
  98 };
  99 MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
 100
 101 #ifdef CONFIG_PM_SLEEP
 102 static int atmel_flexcom_resume(struct device *dev)
 103 {
 104         struct atmel_flexcom *ddata = dev_get_drvdata(dev);
 105         int err;
 106         u32 val;
 107
 108         err = clk_prepare_enable(ddata->clk);
 109         if (err)
 110                 return err;
 111
 112         val = FLEX_MR_OPMODE(ddata->opmode),
 113         writel(val, ddata->base + FLEX_MR);
 114
 115         clk_disable_unprepare(ddata->clk);
 116
 117         return 0;
 118 }
 119 #endif
 120
 121 static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL,
 122                          atmel_flexcom_resume);
 123
 124 static struct platform_driver atmel_flexcom_driver = {
 125         .probe  = atmel_flexcom_probe,
 126         .driver = {
 127                 .name           = "atmel_flexcom",
 128                 .pm             = &atmel_flexcom_pm_ops,
 129                 .of_match_table = atmel_flexcom_of_match,
 130         },
 131 };
 132
 133 module_platform_driver(atmel_flexcom_driver);
 134
 135 MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
 136 MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
 137 MODULE_LICENSE("GPL v2");