1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2016 Imagination Technologies
4 * Author: Paul Burton <paul.burton@mips.com>
5 */
6
7 #include <linux/kernel.h>
8 #include <linux/io.h>
9 #include <linux/mfd/syscon.h>
10 #include <linux/module.h>
11 #include <linux/of_address.h>
12 #include <linux/of_platform.h>
13 #include <linux/platform_device.h>
14 #include <linux/regmap.h>
15 #include <linux/slab.h>
16
17 #include "line-display.h"
18
19 struct img_ascii_lcd_ctx;
20
21 /**
22 * struct img_ascii_lcd_config - Configuration information about an LCD model
23 * @num_chars: the number of characters the LCD can display
24 * @external_regmap: true if registers are in a system controller, else false
25 * @update: function called to update the LCD
26 */
27 struct img_ascii_lcd_config {
28 unsigned int num_chars;
29 bool external_regmap;
30 void (*update)(struct linedisp *linedisp);
31 };
32
33 /**
34 * struct img_ascii_lcd_ctx - Private data structure
35 * @base: the base address of the LCD registers
36 * @regmap: the regmap through which LCD registers are accessed
37 * @offset: the offset within regmap to the start of the LCD registers
38 * @cfg: pointer to the LCD model configuration
39 * @linedisp: line display structure
40 * @curr: the string currently displayed on the LCD
41 */
42 struct img_ascii_lcd_ctx {
43 union {
44 void __iomem *base;
45 struct regmap *regmap;
46 };
47 u32 offset;
48 const struct img_ascii_lcd_config *cfg;
49 struct linedisp linedisp;
50 char curr[] __aligned(8);
51 };
52
53 /*
54 * MIPS Boston development board
55 */
56
boston_update(struct linedisp * linedisp)57 static void boston_update(struct linedisp *linedisp)
58 {
59 struct img_ascii_lcd_ctx *ctx =
60 container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
61 ulong val;
62
63 #if BITS_PER_LONG == 64
64 val = *((u64 *)&ctx->curr[0]);
65 __raw_writeq(val, ctx->base);
66 #elif BITS_PER_LONG == 32
67 val = *((u32 *)&ctx->curr[0]);
68 __raw_writel(val, ctx->base);
69 val = *((u32 *)&ctx->curr[4]);
70 __raw_writel(val, ctx->base + 4);
71 #else
72 # error Not 32 or 64 bit
73 #endif
74 }
75
76 static struct img_ascii_lcd_config boston_config = {
77 .num_chars = 8,
78 .update = boston_update,
79 };
80
81 /*
82 * MIPS Malta development board
83 */
84
malta_update(struct linedisp * linedisp)85 static void malta_update(struct linedisp *linedisp)
86 {
87 struct img_ascii_lcd_ctx *ctx =
88 container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
89 unsigned int i;
90 int err = 0;
91
92 for (i = 0; i < linedisp->num_chars; i++) {
93 err = regmap_write(ctx->regmap,
94 ctx->offset + (i * 8), ctx->curr[i]);
95 if (err)
96 break;
97 }
98
99 if (unlikely(err))
100 pr_err_ratelimited("Failed to update LCD display: %d\n", err);
101 }
102
103 static struct img_ascii_lcd_config malta_config = {
104 .num_chars = 8,
105 .external_regmap = true,
106 .update = malta_update,
107 };
108
109 /*
110 * MIPS SEAD3 development board
111 */
112
113 enum {
114 SEAD3_REG_LCD_CTRL = 0x00,
115 #define SEAD3_REG_LCD_CTRL_SETDRAM BIT(7)
116 SEAD3_REG_LCD_DATA = 0x08,
117 SEAD3_REG_CPLD_STATUS = 0x10,
118 #define SEAD3_REG_CPLD_STATUS_BUSY BIT(0)
119 SEAD3_REG_CPLD_DATA = 0x18,
120 #define SEAD3_REG_CPLD_DATA_BUSY BIT(7)
121 };
122
sead3_wait_sm_idle(struct img_ascii_lcd_ctx * ctx)123 static int sead3_wait_sm_idle(struct img_ascii_lcd_ctx *ctx)
124 {
125 unsigned int status;
126 int err;
127
128 do {
129 err = regmap_read(ctx->regmap,
130 ctx->offset + SEAD3_REG_CPLD_STATUS,
131 &status);
132 if (err)
133 return err;
134 } while (status & SEAD3_REG_CPLD_STATUS_BUSY);
135
136 return 0;
137
138 }
139
sead3_wait_lcd_idle(struct img_ascii_lcd_ctx * ctx)140 static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx)
141 {
142 unsigned int cpld_data;
143 int err;
144
145 err = sead3_wait_sm_idle(ctx);
146 if (err)
147 return err;
148
149 do {
150 err = regmap_read(ctx->regmap,
151 ctx->offset + SEAD3_REG_LCD_CTRL,
152 &cpld_data);
153 if (err)
154 return err;
155
156 err = sead3_wait_sm_idle(ctx);
157 if (err)
158 return err;
159
160 err = regmap_read(ctx->regmap,
161 ctx->offset + SEAD3_REG_CPLD_DATA,
162 &cpld_data);
163 if (err)
164 return err;
165 } while (cpld_data & SEAD3_REG_CPLD_DATA_BUSY);
166
167 return 0;
168 }
169
sead3_update(struct linedisp * linedisp)170 static void sead3_update(struct linedisp *linedisp)
171 {
172 struct img_ascii_lcd_ctx *ctx =
173 container_of(linedisp, struct img_ascii_lcd_ctx, linedisp);
174 unsigned int i;
175 int err = 0;
176
177 for (i = 0; i < linedisp->num_chars; i++) {
178 err = sead3_wait_lcd_idle(ctx);
179 if (err)
180 break;
181
182 err = regmap_write(ctx->regmap,
183 ctx->offset + SEAD3_REG_LCD_CTRL,
184 SEAD3_REG_LCD_CTRL_SETDRAM | i);
185 if (err)
186 break;
187
188 err = sead3_wait_lcd_idle(ctx);
189 if (err)
190 break;
191
192 err = regmap_write(ctx->regmap,
193 ctx->offset + SEAD3_REG_LCD_DATA,
194 ctx->curr[i]);
195 if (err)
196 break;
197 }
198
199 if (unlikely(err))
200 pr_err_ratelimited("Failed to update LCD display: %d\n", err);
201 }
202
203 static struct img_ascii_lcd_config sead3_config = {
204 .num_chars = 16,
205 .external_regmap = true,
206 .update = sead3_update,
207 };
208
209 static const struct of_device_id img_ascii_lcd_matches[] = {
210 { .compatible = "img,boston-lcd", .data = &boston_config },
211 { .compatible = "mti,malta-lcd", .data = &malta_config },
212 { .compatible = "mti,sead3-lcd", .data = &sead3_config },
213 { /* sentinel */ }
214 };
215 MODULE_DEVICE_TABLE(of, img_ascii_lcd_matches);
216
217 /**
218 * img_ascii_lcd_probe() - probe an LCD display device
219 * @pdev: the LCD platform device
220 *
221 * Probe an LCD display device, ensuring that we have the required resources in
222 * order to access the LCD & setting up private data as well as sysfs files.
223 *
224 * Return: 0 on success, else -ERRNO
225 */
img_ascii_lcd_probe(struct platform_device * pdev)226 static int img_ascii_lcd_probe(struct platform_device *pdev)
227 {
228 const struct of_device_id *match;
229 const struct img_ascii_lcd_config *cfg;
230 struct device *dev = &pdev->dev;
231 struct img_ascii_lcd_ctx *ctx;
232 int err;
233
234 match = of_match_device(img_ascii_lcd_matches, dev);
235 if (!match)
236 return -ENODEV;
237
238 cfg = match->data;
239 ctx = devm_kzalloc(dev, sizeof(*ctx) + cfg->num_chars, GFP_KERNEL);
240 if (!ctx)
241 return -ENOMEM;
242
243 if (cfg->external_regmap) {
244 ctx->regmap = syscon_node_to_regmap(dev->parent->of_node);
245 if (IS_ERR(ctx->regmap))
246 return PTR_ERR(ctx->regmap);
247
248 if (of_property_read_u32(dev->of_node, "offset", &ctx->offset))
249 return -EINVAL;
250 } else {
251 ctx->base = devm_platform_ioremap_resource(pdev, 0);
252 if (IS_ERR(ctx->base))
253 return PTR_ERR(ctx->base);
254 }
255
256 err = linedisp_register(&ctx->linedisp, dev, cfg->num_chars, ctx->curr,
257 cfg->update);
258 if (err)
259 return err;
260
261 /* for backwards compatibility */
262 err = compat_only_sysfs_link_entry_to_kobj(&dev->kobj,
263 &ctx->linedisp.dev.kobj,
264 "message", NULL);
265 if (err)
266 goto err_unregister;
267
268 platform_set_drvdata(pdev, ctx);
269 return 0;
270
271 err_unregister:
272 linedisp_unregister(&ctx->linedisp);
273 return err;
274 }
275
276 /**
277 * img_ascii_lcd_remove() - remove an LCD display device
278 * @pdev: the LCD platform device
279 *
280 * Remove an LCD display device, freeing private resources & ensuring that the
281 * driver stops using the LCD display registers.
282 *
283 * Return: 0
284 */
img_ascii_lcd_remove(struct platform_device * pdev)285 static int img_ascii_lcd_remove(struct platform_device *pdev)
286 {
287 struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev);
288
289 sysfs_remove_link(&pdev->dev.kobj, "message");
290 linedisp_unregister(&ctx->linedisp);
291 return 0;
292 }
293
294 static struct platform_driver img_ascii_lcd_driver = {
295 .driver = {
296 .name = "img-ascii-lcd",
297 .of_match_table = img_ascii_lcd_matches,
298 },
299 .probe = img_ascii_lcd_probe,
300 .remove = img_ascii_lcd_remove,
301 };
302 module_platform_driver(img_ascii_lcd_driver);
303
304 MODULE_DESCRIPTION("Imagination Technologies ASCII LCD Display");
305 MODULE_AUTHOR("Paul Burton <paul.burton@mips.com>");
306 MODULE_LICENSE("GPL");
307