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
29 struct da8xx_ddrctl_config_knob {
30 const char *name;
31 u32 reg;
32 u32 mask;
33 u32 shift;
34 };
35
36 static 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
45 struct da8xx_ddrctl_setting {
46 const char *name;
47 u32 val;
48 };
49
50 struct da8xx_ddrctl_board_settings {
51 const char *board;
52 const struct da8xx_ddrctl_setting *settings;
53 };
54
55 static const struct da8xx_ddrctl_setting da850_lcdk_ddrctl_settings[] = {
56 {
57 .name = "da850-pbbpr",
58 .val = 0x20,
59 },
60 { }
61 };
62
63 static 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
70 static const struct da8xx_ddrctl_config_knob *
da8xx_ddrctl_match_knob(const struct da8xx_ddrctl_setting * setting)71 da8xx_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
da8xx_ddrctl_get_board_settings(void)86 static 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
da8xx_ddrctl_probe(struct platform_device * pdev)101 static 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 ddrctl = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
119 if (IS_ERR(ddrctl)) {
120 dev_err(dev, "unable to map memory controller registers\n");
121 return PTR_ERR(ddrctl);
122 }
123
124 for (; setting->name; setting++) {
125 knob = da8xx_ddrctl_match_knob(setting);
126 if (!knob) {
127 dev_warn(dev,
128 "no such config option: %s\n", setting->name);
129 continue;
130 }
131
132 if (knob->reg + sizeof(u32) > resource_size(res)) {
133 dev_warn(dev,
134 "register offset of '%s' exceeds mapped memory size\n",
135 knob->name);
136 continue;
137 }
138
139 reg = readl(ddrctl + knob->reg);
140 reg &= knob->mask;
141 reg |= setting->val << knob->shift;
142
143 dev_dbg(dev, "writing 0x%08x to %s\n", reg, setting->name);
144
145 writel(reg, ddrctl + knob->reg);
146 }
147
148 return 0;
149 }
150
151 static const struct of_device_id da8xx_ddrctl_of_match[] = {
152 { .compatible = "ti,da850-ddr-controller", },
153 { },
154 };
155
156 static struct platform_driver da8xx_ddrctl_driver = {
157 .probe = da8xx_ddrctl_probe,
158 .driver = {
159 .name = "da850-ddr-controller",
160 .of_match_table = da8xx_ddrctl_of_match,
161 },
162 };
163 module_platform_driver(da8xx_ddrctl_driver);
164
165 MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
166 MODULE_DESCRIPTION("TI da8xx DDR2/mDDR controller driver");
167 MODULE_LICENSE("GPL v2");
168