/*
* TI da8xx DDR2/mDDR controller driver
*
* Copyright (C) 2016 BayLibre SAS
*
* Author:
* Bartosz Golaszewski <bgolaszewski@baylibre.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/io.h>
/*
* REVISIT: Linux doesn't have a good framework for the kind of performance
* knobs this driver controls. We can't use device tree properties as it deals
* with hardware configuration rather than description. We also don't want to
* commit to maintaining some random sysfs attributes.
*
* For now we just hardcode the register values for the boards that need
* some changes (as is the case for the LCD controller on da850-lcdk - the
* first board we support here). When linux gets an appropriate framework,
* we'll easily convert the driver to it.
*/
struct da8xx_ddrctl_config_knob {
const char *name;
u32 reg;
u32 mask;
u32 shift;
};
static const struct da8xx_ddrctl_config_knob da8xx_ddrctl_knobs[] = {
{
.name = "da850-pbbpr",
.reg = 0x20,
.mask = 0xffffff00,
.shift = 0,
},
};
struct da8xx_ddrctl_setting {
const char *name;
u32 val;
};
struct da8xx_ddrctl_board_settings {
const char *board;
const struct da8xx_ddrctl_setting *settings;
};
static const struct da8xx_ddrctl_setting da850_lcdk_ddrctl_settings[] = {
{
.name = "da850-pbbpr",
.val = 0x20,
},
{ }
};
static const struct da8xx_ddrctl_board_settings da8xx_ddrctl_board_confs[] = {
{
.board = "ti,da850-lcdk",
.settings = da850_lcdk_ddrctl_settings,
},
};
static const struct da8xx_ddrctl_config_knob *
da8xx_ddrctl_match_knob(const struct da8xx_ddrctl_setting *setting)
{
const struct da8xx_ddrctl_config_knob *knob;
int i;
for (i = 0; i < ARRAY_SIZE(da8xx_ddrctl_knobs); i++) {
knob = &da8xx_ddrctl_knobs[i];
if (strcmp(knob->name, setting->name) == 0)
return knob;
}
return NULL;
}
static const struct da8xx_ddrctl_setting *da8xx_ddrctl_get_board_settings(void)
{
const struct da8xx_ddrctl_board_settings *board_settings;
int i;
for (i = 0; i < ARRAY_SIZE(da8xx_ddrctl_board_confs); i++) {
board_settings = &da8xx_ddrctl_board_confs[i];
if (of_machine_is_compatible(board_settings->board))
return board_settings->settings;
}
return NULL;
}
static int da8xx_ddrctl_probe(struct platform_device *pdev)
{
const struct da8xx_ddrctl_config_knob *knob;
const struct da8xx_ddrctl_setting *setting;
struct device_node *node;
struct resource *res;
void __iomem *ddrctl;
struct device *dev;
u32 reg;
dev = &pdev->dev;
node = dev->of_node;
setting = da8xx_ddrctl_get_board_settings();
if (!setting) {
dev_err(dev, "no settings defined for this board\n");
return -EINVAL;
}
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
ddrctl = devm_ioremap_resource(dev, res);
if (IS_ERR(ddrctl)) {
dev_err(dev, "unable to map memory controller registers\n");
return PTR_ERR(ddrctl);
}
for (; setting->name; setting++) {
knob = da8xx_ddrctl_match_knob(setting);
if (!knob) {
dev_warn(dev,
"no such config option: %s\n", setting->name);
continue;
}
if (knob->reg + sizeof(u32) > resource_size(res)) {
dev_warn(dev,
"register offset of '%s' exceeds mapped memory size\n",
knob->name);
continue;
}
reg = readl(ddrctl + knob->reg);
reg &= knob->mask;
reg |= setting->val << knob->shift;
dev_dbg(dev, "writing 0x%08x to %s\n", reg, setting->name);
writel(reg, ddrctl + knob->reg);
}
return 0;
}
static const struct of_device_id da8xx_ddrctl_of_match[] = {
{ .compatible = "ti,da850-ddr-controller", },
{ },
};
static struct platform_driver da8xx_ddrctl_driver = {
.probe = da8xx_ddrctl_probe,
.driver = {
.name = "da850-ddr-controller",
.of_match_table = da8xx_ddrctl_of_match,
},
};
module_platform_driver(da8xx_ddrctl_driver);
MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
MODULE_DESCRIPTION("TI da8xx DDR2/mDDR controller driver");
MODULE_LICENSE("GPL v2");
