LXR linux/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 <bgolaszewski@baylibre.com>
   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
  32struct da8xx_ddrctl_config_knob {
  33        const char *name;
  34        u32 reg;
  35        u32 mask;
  36        u32 shift;
  37};
  38
  39static 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
  48struct da8xx_ddrctl_setting {
  49        const char *name;
  50        u32 val;
  51};
  52
  53struct da8xx_ddrctl_board_settings {
  54        const char *board;
  55        const struct da8xx_ddrctl_setting *settings;
  56};
  57
  58static const struct da8xx_ddrctl_setting da850_lcdk_ddrctl_settings[] = {
  59        {
  60                .name = "da850-pbbpr",
  61                .val = 0x20,
  62        },
  63        { }
  64};
  65
  66static 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
  73static const struct da8xx_ddrctl_config_knob *
  74da8xx_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
  89static 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
 104static 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
 157static const struct of_device_id da8xx_ddrctl_of_match[] = {
 158        { .compatible = "ti,da850-ddr-controller", },
 159        { },
 160};
 161
 162static 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};
 169module_platform_driver(da8xx_ddrctl_driver);
 170
 171MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
 172MODULE_DESCRIPTION("TI da8xx DDR2/mDDR controller driver");
 173MODULE_LICENSE("GPL v2");
 174