drivers/memory/da8xx-ddrctl.c

   1 /*
   2  * TI da8xx DDR2/mDDR controller driver
   3  *
   4  * Copyright (C) 2016 BayLibre SAS
   5  *
   6  * Author:
   7  *   Bartosz Golaszewski <[email protected]>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/of_device.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/io.h>
  19
  20 /*
  21  * REVISIT: Linux doesn't have a good framework for the kind of performance
  22  * knobs this driver controls. We can't use device tree properties as it deals
  23  * with hardware configuration rather than description. We also don't want to
  24  * commit to maintaining some random sysfs attributes.
  25  *
  26  * For now we just hardcode the register values for the boards that need
  27  * some changes (as is the case for the LCD controller on da850-lcdk - the
  28  * first board we support here). When linux gets an appropriate framework,
  29  * we'll easily convert the driver to it.
  30  */
  31
  32 struct da8xx_ddrctl_config_knob {
  33         const char *name;
  34         u32 reg;
  35         u32 mask;
  36         u32 shift;
  37 };
  38
  39 static const struct da8xx_ddrctl_config_knob da8xx_ddrctl_knobs[] = {
  40         {
  41                 .name = "da850-pbbpr",
  42                 .reg = 0x20,
  43                 .mask = 0xffffff00,
  44                 .shift = 0,
  45         },
  46 };
  47
  48 struct da8xx_ddrctl_setting {
  49         const char *name;
  50         u32 val;
  51 };
  52
  53 struct da8xx_ddrctl_board_settings {
  54         const char *board;
  55         const struct da8xx_ddrctl_setting *settings;
  56 };
  57
  58 static const struct da8xx_ddrctl_setting da850_lcdk_ddrctl_settings[] = {
  59         {
  60                 .name = "da850-pbbpr",
  61                 .val = 0x20,
  62         },
  63         { }
  64 };
  65
  66 static const struct da8xx_ddrctl_board_settings da8xx_ddrctl_board_confs[] = {
  67         {
  68                 .board = "ti,da850-lcdk",
  69                 .settings = da850_lcdk_ddrctl_settings,
  70         },
  71 };
  72
  73 static const struct da8xx_ddrctl_config_knob *
  74 da8xx_ddrctl_match_knob(const struct da8xx_ddrctl_setting *setting)
  75 {
  76         const struct da8xx_ddrctl_config_knob *knob;
  77         int i;
  78
  79         for (i = 0; i < ARRAY_SIZE(da8xx_ddrctl_knobs); i++) {
  80                 knob = &da8xx_ddrctl_knobs[i];
  81
  82                 if (strcmp(knob->name, setting->name) == 0)
  83                         return knob;
  84         }
  85
  86         return NULL;
  87 }
  88
  89 static const struct da8xx_ddrctl_setting *da8xx_ddrctl_get_board_settings(void)
  90 {
  91         const struct da8xx_ddrctl_board_settings *board_settings;
  92         int i;
  93
  94         for (i = 0; i < ARRAY_SIZE(da8xx_ddrctl_board_confs); i++) {
  95                 board_settings = &da8xx_ddrctl_board_confs[i];
  96
  97                 if (of_machine_is_compatible(board_settings->board))
  98                         return board_settings->settings;
  99         }
 100
 101         return NULL;
 102 }
 103
 104 static int da8xx_ddrctl_probe(struct platform_device *pdev)
 105 {
 106         const struct da8xx_ddrctl_config_knob *knob;
 107         const struct da8xx_ddrctl_setting *setting;
 108         struct device_node *node;
 109         struct resource *res;
 110         void __iomem *ddrctl;
 111         struct device *dev;
 112         u32 reg;
 113
 114         dev = &pdev->dev;
 115         node = dev->of_node;
 116
 117         setting = da8xx_ddrctl_get_board_settings();
 118         if (!setting) {
 119                 dev_err(dev, "no settings defined for this board\n");
 120                 return -EINVAL;
 121         }
 122
 123         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 124         ddrctl = devm_ioremap_resource(dev, res);
 125         if (IS_ERR(ddrctl)) {
 126                 dev_err(dev, "unable to map memory controller registers\n");
 127                 return PTR_ERR(ddrctl);
 128         }
 129
 130         for (; setting->name; setting++) {
 131                 knob = da8xx_ddrctl_match_knob(setting);
 132                 if (!knob) {
 133                         dev_warn(dev,
 134                                  "no such config option: %s\n", setting->name);
 135                         continue;
 136                 }
 137
 138                 if (knob->reg + sizeof(u32) > resource_size(res)) {
 139                         dev_warn(dev,
 140                                  "register offset of '%s' exceeds mapped memory size\n",
 141                                  knob->name);
 142                         continue;
 143                 }
 144
 145                 reg = readl(ddrctl + knob->reg);
 146                 reg &= knob->mask;
 147                 reg |= setting->val << knob->shift;
 148
 149                 dev_dbg(dev, "writing 0x%08x to %s\n", reg, setting->name);
 150
 151                 writel(reg, ddrctl + knob->reg);
 152         }
 153
 154         return 0;
 155 }
 156
 157 static const struct of_device_id da8xx_ddrctl_of_match[] = {
 158         { .compatible = "ti,da850-ddr-controller", },
 159         { },
 160 };
 161
 162 static struct platform_driver da8xx_ddrctl_driver = {
 163         .probe = da8xx_ddrctl_probe,
 164         .driver = {
 165                 .name = "da850-ddr-controller",
 166                 .of_match_table = da8xx_ddrctl_of_match,
 167         },
 168 };
 169 module_platform_driver(da8xx_ddrctl_driver);
 170
 171 MODULE_AUTHOR("Bartosz Golaszewski <[email protected]>");
 172 MODULE_DESCRIPTION("TI da8xx DDR2/mDDR controller driver");
 173 MODULE_LICENSE("GPL v2");