xref: /openbmc/linux/drivers/memory/da8xx-ddrctl.c (revision 0b483871)
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 
28 struct da8xx_ddrctl_config_knob {
29 	const char *name;
30 	u32 reg;
31 	u32 mask;
32 	u32 shift;
33 };
34 
35 static 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 
44 struct da8xx_ddrctl_setting {
45 	const char *name;
46 	u32 val;
47 };
48 
49 struct da8xx_ddrctl_board_settings {
50 	const char *board;
51 	const struct da8xx_ddrctl_setting *settings;
52 };
53 
54 static const struct da8xx_ddrctl_setting da850_lcdk_ddrctl_settings[] = {
55 	{
56 		.name = "da850-pbbpr",
57 		.val = 0x20,
58 	},
59 	{ }
60 };
61 
62 static 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 
69 static const struct da8xx_ddrctl_config_knob *
da8xx_ddrctl_match_knob(const struct da8xx_ddrctl_setting * setting)70 da8xx_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 
da8xx_ddrctl_get_board_settings(void)85 static 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 
da8xx_ddrctl_probe(struct platform_device * pdev)100 static 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 
150 static const struct of_device_id da8xx_ddrctl_of_match[] = {
151 	{ .compatible = "ti,da850-ddr-controller", },
152 	{ },
153 };
154 
155 static 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 };
162 module_platform_driver(da8xx_ddrctl_driver);
163 
164 MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
165 MODULE_DESCRIPTION("TI da8xx DDR2/mDDR controller driver");
166