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");