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");