drivers/nvmem/snvs_lpgpr.c

   1 /*
   2  * Copyright (c) 2015 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>
   3  * Copyright (c) 2017 Pengutronix, Oleksij Rempel <kernel@pengutronix.de>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2
   7  * as published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/mfd/syscon.h>
  11 #include <linux/module.h>
  12 #include <linux/nvmem-provider.h>
  13 #include <linux/of_device.h>
  14 #include <linux/regmap.h>
  15
  16 #define IMX6Q_SNVS_HPLR         0x00
  17 #define IMX6Q_GPR_SL            BIT(5)
  18 #define IMX6Q_SNVS_LPLR         0x34
  19 #define IMX6Q_GPR_HL            BIT(5)
  20 #define IMX6Q_SNVS_LPGPR        0x68
  21
  22 struct snvs_lpgpr_cfg {
  23         int offset;
  24         int offset_hplr;
  25         int offset_lplr;
  26 };
  27
  28 struct snvs_lpgpr_priv {
  29         struct device_d                 *dev;
  30         struct regmap                   *regmap;
  31         struct nvmem_config             cfg;
  32         const struct snvs_lpgpr_cfg     *dcfg;
  33 };
  34
  35 static const struct snvs_lpgpr_cfg snvs_lpgpr_cfg_imx6q = {
  36         .offset         = IMX6Q_SNVS_LPGPR,
  37         .offset_hplr    = IMX6Q_SNVS_HPLR,
  38         .offset_lplr    = IMX6Q_SNVS_LPLR,
  39 };
  40
  41 static int snvs_lpgpr_write(void *context, unsigned int offset, void *val,
  42                             size_t bytes)
  43 {
  44         struct snvs_lpgpr_priv *priv = context;
  45         const struct snvs_lpgpr_cfg *dcfg = priv->dcfg;
  46         unsigned int lock_reg;
  47         int ret;
  48
  49         ret = regmap_read(priv->regmap, dcfg->offset_hplr, &lock_reg);
  50         if (ret < 0)
  51                 return ret;
  52
  53         if (lock_reg & IMX6Q_GPR_SL)
  54                 return -EPERM;
  55
  56         ret = regmap_read(priv->regmap, dcfg->offset_lplr, &lock_reg);
  57         if (ret < 0)
  58                 return ret;
  59
  60         if (lock_reg & IMX6Q_GPR_HL)
  61                 return -EPERM;
  62
  63         return regmap_bulk_write(priv->regmap, dcfg->offset + offset, val,
  64                                 bytes / 4);
  65 }
  66
  67 static int snvs_lpgpr_read(void *context, unsigned int offset, void *val,
  68                            size_t bytes)
  69 {
  70         struct snvs_lpgpr_priv *priv = context;
  71         const struct snvs_lpgpr_cfg *dcfg = priv->dcfg;
  72
  73         return regmap_bulk_read(priv->regmap, dcfg->offset + offset,
  74                                val, bytes / 4);
  75 }
  76
  77 static int snvs_lpgpr_probe(struct platform_device *pdev)
  78 {
  79         struct device *dev = &pdev->dev;
  80         struct device_node *node = dev->of_node;
  81         struct device_node *syscon_node;
  82         struct snvs_lpgpr_priv *priv;
  83         struct nvmem_config *cfg;
  84         struct nvmem_device *nvmem;
  85         const struct snvs_lpgpr_cfg *dcfg;
  86
  87         if (!node)
  88                 return -ENOENT;
  89
  90         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
  91         if (!priv)
  92                 return -ENOMEM;
  93
  94         dcfg = of_device_get_match_data(dev);
  95         if (!dcfg)
  96                 return -EINVAL;
  97
  98         syscon_node = of_get_parent(node);
  99         if (!syscon_node)
 100                 return -ENODEV;
 101
 102         priv->regmap = syscon_node_to_regmap(syscon_node);
 103         of_node_put(syscon_node);
 104         if (IS_ERR(priv->regmap))
 105                 return PTR_ERR(priv->regmap);
 106
 107         priv->dcfg = dcfg;
 108
 109         cfg = &priv->cfg;
 110         cfg->priv = priv;
 111         cfg->name = dev_name(dev);
 112         cfg->dev = dev;
 113         cfg->stride = 4,
 114         cfg->word_size = 4,
 115         cfg->size = 4,
 116         cfg->owner = THIS_MODULE,
 117         cfg->reg_read  = snvs_lpgpr_read,
 118         cfg->reg_write = snvs_lpgpr_write,
 119
 120         nvmem = nvmem_register(cfg);
 121         if (IS_ERR(nvmem))
 122                 return PTR_ERR(nvmem);
 123
 124         platform_set_drvdata(pdev, nvmem);
 125
 126         return 0;
 127 }
 128
 129 static int snvs_lpgpr_remove(struct platform_device *pdev)
 130 {
 131         struct nvmem_device *nvmem = platform_get_drvdata(pdev);
 132
 133         return nvmem_unregister(nvmem);
 134 }
 135
 136 static const struct of_device_id snvs_lpgpr_dt_ids[] = {
 137         { .compatible = "fsl,imx6q-snvs-lpgpr", .data = &snvs_lpgpr_cfg_imx6q },
 138         { .compatible = "fsl,imx6ul-snvs-lpgpr",
 139           .data = &snvs_lpgpr_cfg_imx6q },
 140         { },
 141 };
 142 MODULE_DEVICE_TABLE(of, snvs_lpgpr_dt_ids);
 143
 144 static struct platform_driver snvs_lpgpr_driver = {
 145         .probe  = snvs_lpgpr_probe,
 146         .remove = snvs_lpgpr_remove,
 147         .driver = {
 148                 .name   = "snvs_lpgpr",
 149                 .of_match_table = snvs_lpgpr_dt_ids,
 150         },
 151 };
 152 module_platform_driver(snvs_lpgpr_driver);
 153
 154 MODULE_AUTHOR("Oleksij Rempel <o.rempel@pengutronix.de>");
 155 MODULE_DESCRIPTION("Low Power General Purpose Register in i.MX6 Secure Non-Volatile Storage");
 156 MODULE_LICENSE("GPL v2");