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