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