1/* Copyright (c) 2009-2013, The Linux Foundation. All rights reserved.
2 * Copyright (c) 2010, Google Inc.
3 *
4 * Original authors: Code Aurora Forum
5 *
6 * Author: Dima Zavin <dima@android.com>
7 * - Largely rewritten from original to not be an i2c driver.
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 and
11 * only version 2 as published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 */
18
19#define pr_fmt(fmt) "%s: " fmt, __func__
20
21#include <linux/delay.h>
22#include <linux/err.h>
23#include <linux/io.h>
24#include <linux/kernel.h>
25#include <linux/platform_device.h>
26#include <linux/slab.h>
27#include <linux/ssbi.h>
28#include <linux/module.h>
29#include <linux/of.h>
30#include <linux/of_device.h>
31
32/* SSBI 2.0 controller registers */
33#define SSBI2_CMD 0x0008
34#define SSBI2_RD 0x0010
35#define SSBI2_STATUS 0x0014
36#define SSBI2_MODE2 0x001C
37
38/* SSBI_CMD fields */
39#define SSBI_CMD_RDWRN (1 << 24)
40
41/* SSBI_STATUS fields */
42#define SSBI_STATUS_RD_READY (1 << 2)
43#define SSBI_STATUS_READY (1 << 1)
44#define SSBI_STATUS_MCHN_BUSY (1 << 0)
45
46/* SSBI_MODE2 fields */
47#define SSBI_MODE2_REG_ADDR_15_8_SHFT 0x04
48#define SSBI_MODE2_REG_ADDR_15_8_MASK (0x7f << SSBI_MODE2_REG_ADDR_15_8_SHFT)
49
50#define SET_SSBI_MODE2_REG_ADDR_15_8(MD, AD) \
51 (((MD) & 0x0F) | ((((AD) >> 8) << SSBI_MODE2_REG_ADDR_15_8_SHFT) & \
52 SSBI_MODE2_REG_ADDR_15_8_MASK))
53
54/* SSBI PMIC Arbiter command registers */
55#define SSBI_PA_CMD 0x0000
56#define SSBI_PA_RD_STATUS 0x0004
57
58/* SSBI_PA_CMD fields */
59#define SSBI_PA_CMD_RDWRN (1 << 24)
60#define SSBI_PA_CMD_ADDR_MASK 0x7fff /* REG_ADDR_7_0, REG_ADDR_8_14*/
61
62/* SSBI_PA_RD_STATUS fields */
63#define SSBI_PA_RD_STATUS_TRANS_DONE (1 << 27)
64#define SSBI_PA_RD_STATUS_TRANS_DENIED (1 << 26)
65
66#define SSBI_TIMEOUT_US 100
67
68enum ssbi_controller_type {
69 MSM_SBI_CTRL_SSBI = 0,
70 MSM_SBI_CTRL_SSBI2,
71 MSM_SBI_CTRL_PMIC_ARBITER,
72};
73
74struct ssbi {
75 struct device *slave;
76 void __iomem *base;
77 spinlock_t lock;
78 enum ssbi_controller_type controller_type;
79 int (*read)(struct ssbi *, u16 addr, u8 *buf, int len);
80 int (*write)(struct ssbi *, u16 addr, const u8 *buf, int len);
81};
82
83#define to_ssbi(dev) platform_get_drvdata(to_platform_device(dev))
84
85static inline u32 ssbi_readl(struct ssbi *ssbi, u32 reg)
86{
87 return readl(ssbi->base + reg);
88}
89
90static inline void ssbi_writel(struct ssbi *ssbi, u32 val, u32 reg)
91{
92 writel(val, ssbi->base + reg);
93}
94
95/*
96 * Via private exchange with one of the original authors, the hardware
97 * should generally finish a transaction in about 5us. The worst
98 * case, is when using the arbiter and both other CPUs have just
99 * started trying to use the SSBI bus will result in a time of about
100 * 20us. It should never take longer than this.
101 *
102 * As such, this wait merely spins, with a udelay.
103 */
104static int ssbi_wait_mask(struct ssbi *ssbi, u32 set_mask, u32 clr_mask)
105{
106 u32 timeout = SSBI_TIMEOUT_US;
107 u32 val;
108
109 while (timeout--) {
110 val = ssbi_readl(ssbi, SSBI2_STATUS);
111 if (((val & set_mask) == set_mask) && ((val & clr_mask) == 0))
112 return 0;
113 udelay(1);
114 }
115
116 return -ETIMEDOUT;
117}
118
119static int
120ssbi_read_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
121{
122 u32 cmd = SSBI_CMD_RDWRN | ((addr & 0xff) << 16);
123 int ret = 0;
124
125 if (ssbi->controller_type == MSM_SBI_CTRL_SSBI2) {
126 u32 mode2 = ssbi_readl(ssbi, SSBI2_MODE2);
127 mode2 = SET_SSBI_MODE2_REG_ADDR_15_8(mode2, addr);
128 ssbi_writel(ssbi, mode2, SSBI2_MODE2);
129 }
130
131 while (len) {
132 ret = ssbi_wait_mask(ssbi, SSBI_STATUS_READY, 0);
133 if (ret)
134 goto err;
135
136 ssbi_writel(ssbi, cmd, SSBI2_CMD);
137 ret = ssbi_wait_mask(ssbi, SSBI_STATUS_RD_READY, 0);
138 if (ret)
139 goto err;
140 *buf++ = ssbi_readl(ssbi, SSBI2_RD) & 0xff;
141 len--;
142 }
143
144err:
145 return ret;
146}
147
148static int
149ssbi_write_bytes(struct ssbi *ssbi, u16 addr, const u8 *buf, int len)
150{
151 int ret = 0;
152
153 if (ssbi->controller_type == MSM_SBI_CTRL_SSBI2) {
154 u32 mode2 = ssbi_readl(ssbi, SSBI2_MODE2);
155 mode2 = SET_SSBI_MODE2_REG_ADDR_15_8(mode2, addr);
156 ssbi_writel(ssbi, mode2, SSBI2_MODE2);
157 }
158
159 while (len) {
160 ret = ssbi_wait_mask(ssbi, SSBI_STATUS_READY, 0);
161 if (ret)
162 goto err;
163
164 ssbi_writel(ssbi, ((addr & 0xff) << 16) | *buf, SSBI2_CMD);
165 ret = ssbi_wait_mask(ssbi, 0, SSBI_STATUS_MCHN_BUSY);
166 if (ret)
167 goto err;
168 buf++;
169 len--;
170 }
171
172err:
173 return ret;
174}
175
176/*
177 * See ssbi_wait_mask for an explanation of the time and the
178 * busywait.
179 */
180static inline int
181ssbi_pa_transfer(struct ssbi *ssbi, u32 cmd, u8 *data)
182{
183 u32 timeout = SSBI_TIMEOUT_US;
184 u32 rd_status = 0;
185
186 ssbi_writel(ssbi, cmd, SSBI_PA_CMD);
187
188 while (timeout--) {
189 rd_status = ssbi_readl(ssbi, SSBI_PA_RD_STATUS);
190
191 if (rd_status & SSBI_PA_RD_STATUS_TRANS_DENIED)
192 return -EPERM;
193
194 if (rd_status & SSBI_PA_RD_STATUS_TRANS_DONE) {
195 if (data)
196 *data = rd_status & 0xff;
197 return 0;
198 }
199 udelay(1);
200 }
201
202 return -ETIMEDOUT;
203}
204
205static int
206ssbi_pa_read_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
207{
208 u32 cmd;
209 int ret = 0;
210
211 cmd = SSBI_PA_CMD_RDWRN | (addr & SSBI_PA_CMD_ADDR_MASK) << 8;
212
213 while (len) {
214 ret = ssbi_pa_transfer(ssbi, cmd, buf);
215 if (ret)
216 goto err;
217 buf++;
218 len--;
219 }
220
221err:
222 return ret;
223}
224
225static int
226ssbi_pa_write_bytes(struct ssbi *ssbi, u16 addr, const u8 *buf, int len)
227{
228 u32 cmd;
229 int ret = 0;
230
231 while (len) {
232 cmd = (addr & SSBI_PA_CMD_ADDR_MASK) << 8 | *buf;
233 ret = ssbi_pa_transfer(ssbi, cmd, NULL);
234 if (ret)
235 goto err;
236 buf++;
237 len--;
238 }
239
240err:
241 return ret;
242}
243
244int ssbi_read(struct device *dev, u16 addr, u8 *buf, int len)
245{
246 struct ssbi *ssbi = to_ssbi(dev);
247 unsigned long flags;
248 int ret;
249
250 spin_lock_irqsave(&ssbi->lock, flags);
251 ret = ssbi->read(ssbi, addr, buf, len);
252 spin_unlock_irqrestore(&ssbi->lock, flags);
253
254 return ret;
255}
256EXPORT_SYMBOL_GPL(ssbi_read);
257
258int ssbi_write(struct device *dev, u16 addr, const u8 *buf, int len)
259{
260 struct ssbi *ssbi = to_ssbi(dev);
261 unsigned long flags;
262 int ret;
263
264 spin_lock_irqsave(&ssbi->lock, flags);
265 ret = ssbi->write(ssbi, addr, buf, len);
266 spin_unlock_irqrestore(&ssbi->lock, flags);
267
268 return ret;
269}
270EXPORT_SYMBOL_GPL(ssbi_write);
271
272static int ssbi_probe(struct platform_device *pdev)
273{
274 struct device_node *np = pdev->dev.of_node;
275 struct resource *mem_res;
276 struct ssbi *ssbi;
277 const char *type;
278
279 ssbi = devm_kzalloc(&pdev->dev, sizeof(*ssbi), GFP_KERNEL);
280 if (!ssbi)
281 return -ENOMEM;
282
283 mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
284 ssbi->base = devm_ioremap_resource(&pdev->dev, mem_res);
285 if (IS_ERR(ssbi->base))
286 return PTR_ERR(ssbi->base);
287
288 platform_set_drvdata(pdev, ssbi);
289
290 type = of_get_property(np, "qcom,controller-type", NULL);
291 if (type == NULL) {
292 dev_err(&pdev->dev, "Missing qcom,controller-type property\n");
293 return -EINVAL;
294 }
295 dev_info(&pdev->dev, "SSBI controller type: '%s'\n", type);
296 if (strcmp(type, "ssbi") == 0)
297 ssbi->controller_type = MSM_SBI_CTRL_SSBI;
298 else if (strcmp(type, "ssbi2") == 0)
299 ssbi->controller_type = MSM_SBI_CTRL_SSBI2;
300 else if (strcmp(type, "pmic-arbiter") == 0)
301 ssbi->controller_type = MSM_SBI_CTRL_PMIC_ARBITER;
302 else {
303 dev_err(&pdev->dev, "Unknown qcom,controller-type\n");
304 return -EINVAL;
305 }
306
307 if (ssbi->controller_type == MSM_SBI_CTRL_PMIC_ARBITER) {
308 ssbi->read = ssbi_pa_read_bytes;
309 ssbi->write = ssbi_pa_write_bytes;
310 } else {
311 ssbi->read = ssbi_read_bytes;
312 ssbi->write = ssbi_write_bytes;
313 }
314
315 spin_lock_init(&ssbi->lock);
316
317 return devm_of_platform_populate(&pdev->dev);
318}
319
320static const struct of_device_id ssbi_match_table[] = {
321 { .compatible = "qcom,ssbi" },
322 {}
323};
324MODULE_DEVICE_TABLE(of, ssbi_match_table);
325
326static struct platform_driver ssbi_driver = {
327 .probe = ssbi_probe,
328 .driver = {
329 .name = "ssbi",
330 .of_match_table = ssbi_match_table,
331 },
332};
333module_platform_driver(ssbi_driver);
334
335MODULE_LICENSE("GPL v2");
336MODULE_VERSION("1.0");
337MODULE_ALIAS("platform:ssbi");
338MODULE_AUTHOR("Dima Zavin <dima@android.com>");
339