drivers/memory/da8xx-ddrctl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * TI da8xx DDR2/mDDR controller driver
   4  *
   5  * Copyright (C) 2016 BayLibre SAS
   6  *
   7  * Author:
   8  *   Bartosz Golaszewski <bgolaszewski@baylibre.com>
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/io.h>
  15
  16 /*
  17  * REVISIT: Linux doesn't have a good framework for the kind of performance
  18  * knobs this driver controls. We can't use device tree properties as it deals
  19  * with hardware configuration rather than description. We also don't want to
  20  * commit to maintaining some random sysfs attributes.
  21  *
  22  * For now we just hardcode the register values for the boards that need
  23  * some changes (as is the case for the LCD controller on da850-lcdk - the
  24  * first board we support here). When linux gets an appropriate framework,
  25  * we'll easily convert the driver to it.
  26  */
  27
  28 struct da8xx_ddrctl_config_knob {
  29         const char *name;
  30         u32 reg;
  31         u32 mask;
  32         u32 shift;
  33 };
  34
  35 static const struct da8xx_ddrctl_config_knob da8xx_ddrctl_knobs[] = {
  36         {
  37                 .name = "da850-pbbpr",
  38                 .reg = 0x20,
  39                 .mask = 0xffffff00,
  40                 .shift = 0,
  41         },
  42 };
  43
  44 struct da8xx_ddrctl_setting {
  45         const char *name;
  46         u32 val;
  47 };
  48
  49 struct da8xx_ddrctl_board_settings {
  50         const char *board;
  51         const struct da8xx_ddrctl_setting *settings;
  52 };
  53
  54 static const struct da8xx_ddrctl_setting da850_lcdk_ddrctl_settings[] = {
  55         {
  56                 .name = "da850-pbbpr",
  57                 .val = 0x20,
  58         },
  59         { }
  60 };
  61
  62 static const struct da8xx_ddrctl_board_settings da8xx_ddrctl_board_confs[] = {
  63         {
  64                 .board = "ti,da850-lcdk",
  65                 .settings = da850_lcdk_ddrctl_settings,
  66         },
  67 };
  68
  69 static const struct da8xx_ddrctl_config_knob *
  70 da8xx_ddrctl_match_knob(const struct da8xx_ddrctl_setting *setting)
  71 {
  72         const struct da8xx_ddrctl_config_knob *knob;
  73         int i;
  74
  75         for (i = 0; i < ARRAY_SIZE(da8xx_ddrctl_knobs); i++) {
  76                 knob = &da8xx_ddrctl_knobs[i];
  77
  78                 if (strcmp(knob->name, setting->name) == 0)
  79                         return knob;
  80         }
  81
  82         return NULL;
  83 }
  84
  85 static const struct da8xx_ddrctl_setting *da8xx_ddrctl_get_board_settings(void)
  86 {
  87         const struct da8xx_ddrctl_board_settings *board_settings;
  88         int i;
  89
  90         for (i = 0; i < ARRAY_SIZE(da8xx_ddrctl_board_confs); i++) {
  91                 board_settings = &da8xx_ddrctl_board_confs[i];
  92
  93                 if (of_machine_is_compatible(board_settings->board))
  94                         return board_settings->settings;
  95         }
  96
  97         return NULL;
  98 }
  99
 100 static int da8xx_ddrctl_probe(struct platform_device *pdev)
 101 {
 102         const struct da8xx_ddrctl_config_knob *knob;
 103         const struct da8xx_ddrctl_setting *setting;
 104         struct resource *res;
 105         void __iomem *ddrctl;
 106         struct device *dev;
 107         u32 reg;
 108
 109         dev = &pdev->dev;
 110
 111         setting = da8xx_ddrctl_get_board_settings();
 112         if (!setting) {
 113                 dev_err(dev, "no settings defined for this board\n");
 114                 return -EINVAL;
 115         }
 116
 117         ddrctl = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
 118         if (IS_ERR(ddrctl)) {
 119                 dev_err(dev, "unable to map memory controller registers\n");
 120                 return PTR_ERR(ddrctl);
 121         }
 122
 123         for (; setting->name; setting++) {
 124                 knob = da8xx_ddrctl_match_knob(setting);
 125                 if (!knob) {
 126                         dev_warn(dev,
 127                                  "no such config option: %s\n", setting->name);
 128                         continue;
 129                 }
 130
 131                 if (knob->reg + sizeof(u32) > resource_size(res)) {
 132                         dev_warn(dev,
 133                                  "register offset of '%s' exceeds mapped memory size\n",
 134                                  knob->name);
 135                         continue;
 136                 }
 137
 138                 reg = readl(ddrctl + knob->reg);
 139                 reg &= knob->mask;
 140                 reg |= setting->val << knob->shift;
 141
 142                 dev_dbg(dev, "writing 0x%08x to %s\n", reg, setting->name);
 143
 144                 writel(reg, ddrctl + knob->reg);
 145         }
 146
 147         return 0;
 148 }
 149
 150 static const struct of_device_id da8xx_ddrctl_of_match[] = {
 151         { .compatible = "ti,da850-ddr-controller", },
 152         { },
 153 };
 154
 155 static struct platform_driver da8xx_ddrctl_driver = {
 156         .probe = da8xx_ddrctl_probe,
 157         .driver = {
 158                 .name = "da850-ddr-controller",
 159                 .of_match_table = da8xx_ddrctl_of_match,
 160         },
 161 };
 162 module_platform_driver(da8xx_ddrctl_driver);
 163
 164 MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
 165 MODULE_DESCRIPTION("TI da8xx DDR2/mDDR controller driver");