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