Linux 5.15-rc6
[muen/linux.git] / drivers / memory / da8xx-ddrctl.c
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 *
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
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
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         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
152 static const struct of_device_id da8xx_ddrctl_of_match[] = {
153         { .compatible = "ti,da850-ddr-controller", },
154         { },
155 };
156
157 static 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 };
164 module_platform_driver(da8xx_ddrctl_driver);
165
166 MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
167 MODULE_DESCRIPTION("TI da8xx DDR2/mDDR controller driver");
168 MODULE_LICENSE("GPL v2");