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1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (c) 2009-2013, The Linux Foundation. All rights reserved.
3 * Copyright (c) 2010, Google Inc.
4 *
5 * Original authors: Code Aurora Forum
6 *
7 * Author: Dima Zavin <dima@android.com>
8 * - Largely rewritten from original to not be an i2c driver.
9 */
10
11#define pr_fmt(fmt) "%s: " fmt, __func__
12
13#include <linux/delay.h>
14#include <linux/err.h>
15#include <linux/io.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/of.h>
19#include <linux/of_platform.h>
20#include <linux/platform_device.h>
21#include <linux/slab.h>
22#include <linux/ssbi.h>
23
24/* SSBI 2.0 controller registers */
25#define SSBI2_CMD 0x0008
26#define SSBI2_RD 0x0010
27#define SSBI2_STATUS 0x0014
28#define SSBI2_MODE2 0x001C
29
30/* SSBI_CMD fields */
31#define SSBI_CMD_RDWRN (1 << 24)
32
33/* SSBI_STATUS fields */
34#define SSBI_STATUS_RD_READY (1 << 2)
35#define SSBI_STATUS_READY (1 << 1)
36#define SSBI_STATUS_MCHN_BUSY (1 << 0)
37
38/* SSBI_MODE2 fields */
39#define SSBI_MODE2_REG_ADDR_15_8_SHFT 0x04
40#define SSBI_MODE2_REG_ADDR_15_8_MASK (0x7f << SSBI_MODE2_REG_ADDR_15_8_SHFT)
41
42#define SET_SSBI_MODE2_REG_ADDR_15_8(MD, AD) \
43 (((MD) & 0x0F) | ((((AD) >> 8) << SSBI_MODE2_REG_ADDR_15_8_SHFT) & \
44 SSBI_MODE2_REG_ADDR_15_8_MASK))
45
46/* SSBI PMIC Arbiter command registers */
47#define SSBI_PA_CMD 0x0000
48#define SSBI_PA_RD_STATUS 0x0004
49
50/* SSBI_PA_CMD fields */
51#define SSBI_PA_CMD_RDWRN (1 << 24)
52#define SSBI_PA_CMD_ADDR_MASK 0x7fff /* REG_ADDR_7_0, REG_ADDR_8_14*/
53
54/* SSBI_PA_RD_STATUS fields */
55#define SSBI_PA_RD_STATUS_TRANS_DONE (1 << 27)
56#define SSBI_PA_RD_STATUS_TRANS_DENIED (1 << 26)
57
58#define SSBI_TIMEOUT_US 100
59
60enum ssbi_controller_type {
61 MSM_SBI_CTRL_SSBI = 0,
62 MSM_SBI_CTRL_SSBI2,
63 MSM_SBI_CTRL_PMIC_ARBITER,
64};
65
66struct ssbi {
67 struct device *slave;
68 void __iomem *base;
69 spinlock_t lock;
70 enum ssbi_controller_type controller_type;
71 int (*read)(struct ssbi *, u16 addr, u8 *buf, int len);
72 int (*write)(struct ssbi *, u16 addr, const u8 *buf, int len);
73};
74
75static inline u32 ssbi_readl(struct ssbi *ssbi, u32 reg)
76{
77 return readl(ssbi->base + reg);
78}
79
80static inline void ssbi_writel(struct ssbi *ssbi, u32 val, u32 reg)
81{
82 writel(val, ssbi->base + reg);
83}
84
85/*
86 * Via private exchange with one of the original authors, the hardware
87 * should generally finish a transaction in about 5us. The worst
88 * case, is when using the arbiter and both other CPUs have just
89 * started trying to use the SSBI bus will result in a time of about
90 * 20us. It should never take longer than this.
91 *
92 * As such, this wait merely spins, with a udelay.
93 */
94static int ssbi_wait_mask(struct ssbi *ssbi, u32 set_mask, u32 clr_mask)
95{
96 u32 timeout = SSBI_TIMEOUT_US;
97 u32 val;
98
99 while (timeout--) {
100 val = ssbi_readl(ssbi, SSBI2_STATUS);
101 if (((val & set_mask) == set_mask) && ((val & clr_mask) == 0))
102 return 0;
103 udelay(1);
104 }
105
106 return -ETIMEDOUT;
107}
108
109static int
110ssbi_read_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
111{
112 u32 cmd = SSBI_CMD_RDWRN | ((addr & 0xff) << 16);
113 int ret = 0;
114
115 if (ssbi->controller_type == MSM_SBI_CTRL_SSBI2) {
116 u32 mode2 = ssbi_readl(ssbi, SSBI2_MODE2);
117 mode2 = SET_SSBI_MODE2_REG_ADDR_15_8(mode2, addr);
118 ssbi_writel(ssbi, mode2, SSBI2_MODE2);
119 }
120
121 while (len) {
122 ret = ssbi_wait_mask(ssbi, SSBI_STATUS_READY, 0);
123 if (ret)
124 goto err;
125
126 ssbi_writel(ssbi, cmd, SSBI2_CMD);
127 ret = ssbi_wait_mask(ssbi, SSBI_STATUS_RD_READY, 0);
128 if (ret)
129 goto err;
130 *buf++ = ssbi_readl(ssbi, SSBI2_RD) & 0xff;
131 len--;
132 }
133
134err:
135 return ret;
136}
137
138static int
139ssbi_write_bytes(struct ssbi *ssbi, u16 addr, const u8 *buf, int len)
140{
141 int ret = 0;
142
143 if (ssbi->controller_type == MSM_SBI_CTRL_SSBI2) {
144 u32 mode2 = ssbi_readl(ssbi, SSBI2_MODE2);
145 mode2 = SET_SSBI_MODE2_REG_ADDR_15_8(mode2, addr);
146 ssbi_writel(ssbi, mode2, SSBI2_MODE2);
147 }
148
149 while (len) {
150 ret = ssbi_wait_mask(ssbi, SSBI_STATUS_READY, 0);
151 if (ret)
152 goto err;
153
154 ssbi_writel(ssbi, ((addr & 0xff) << 16) | *buf, SSBI2_CMD);
155 ret = ssbi_wait_mask(ssbi, 0, SSBI_STATUS_MCHN_BUSY);
156 if (ret)
157 goto err;
158 buf++;
159 len--;
160 }
161
162err:
163 return ret;
164}
165
166/*
167 * See ssbi_wait_mask for an explanation of the time and the
168 * busywait.
169 */
170static inline int
171ssbi_pa_transfer(struct ssbi *ssbi, u32 cmd, u8 *data)
172{
173 u32 timeout = SSBI_TIMEOUT_US;
174 u32 rd_status = 0;
175
176 ssbi_writel(ssbi, cmd, SSBI_PA_CMD);
177
178 while (timeout--) {
179 rd_status = ssbi_readl(ssbi, SSBI_PA_RD_STATUS);
180
181 if (rd_status & SSBI_PA_RD_STATUS_TRANS_DENIED)
182 return -EPERM;
183
184 if (rd_status & SSBI_PA_RD_STATUS_TRANS_DONE) {
185 if (data)
186 *data = rd_status & 0xff;
187 return 0;
188 }
189 udelay(1);
190 }
191
192 return -ETIMEDOUT;
193}
194
195static int
196ssbi_pa_read_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
197{
198 u32 cmd;
199 int ret = 0;
200
201 cmd = SSBI_PA_CMD_RDWRN | (addr & SSBI_PA_CMD_ADDR_MASK) << 8;
202
203 while (len) {
204 ret = ssbi_pa_transfer(ssbi, cmd, buf);
205 if (ret)
206 goto err;
207 buf++;
208 len--;
209 }
210
211err:
212 return ret;
213}
214
215static int
216ssbi_pa_write_bytes(struct ssbi *ssbi, u16 addr, const u8 *buf, int len)
217{
218 u32 cmd;
219 int ret = 0;
220
221 while (len) {
222 cmd = (addr & SSBI_PA_CMD_ADDR_MASK) << 8 | *buf;
223 ret = ssbi_pa_transfer(ssbi, cmd, NULL);
224 if (ret)
225 goto err;
226 buf++;
227 len--;
228 }
229
230err:
231 return ret;
232}
233
234int ssbi_read(struct device *dev, u16 addr, u8 *buf, int len)
235{
236 struct ssbi *ssbi = dev_get_drvdata(dev);
237 unsigned long flags;
238 int ret;
239
240 spin_lock_irqsave(&ssbi->lock, flags);
241 ret = ssbi->read(ssbi, addr, buf, len);
242 spin_unlock_irqrestore(&ssbi->lock, flags);
243
244 return ret;
245}
246EXPORT_SYMBOL_GPL(ssbi_read);
247
248int ssbi_write(struct device *dev, u16 addr, const u8 *buf, int len)
249{
250 struct ssbi *ssbi = dev_get_drvdata(dev);
251 unsigned long flags;
252 int ret;
253
254 spin_lock_irqsave(&ssbi->lock, flags);
255 ret = ssbi->write(ssbi, addr, buf, len);
256 spin_unlock_irqrestore(&ssbi->lock, flags);
257
258 return ret;
259}
260EXPORT_SYMBOL_GPL(ssbi_write);
261
262static int ssbi_probe(struct platform_device *pdev)
263{
264 struct device_node *np = pdev->dev.of_node;
265 struct ssbi *ssbi;
266 const char *type;
267
268 ssbi = devm_kzalloc(&pdev->dev, sizeof(*ssbi), GFP_KERNEL);
269 if (!ssbi)
270 return -ENOMEM;
271
272 ssbi->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
273 if (IS_ERR(ssbi->base))
274 return PTR_ERR(ssbi->base);
275
276 platform_set_drvdata(pdev, ssbi);
277
278 type = of_get_property(np, "qcom,controller-type", NULL);
279 if (type == NULL) {
280 dev_err(&pdev->dev, "Missing qcom,controller-type property\n");
281 return -EINVAL;
282 }
283 dev_info(&pdev->dev, "SSBI controller type: '%s'\n", type);
284 if (strcmp(type, "ssbi") == 0)
285 ssbi->controller_type = MSM_SBI_CTRL_SSBI;
286 else if (strcmp(type, "ssbi2") == 0)
287 ssbi->controller_type = MSM_SBI_CTRL_SSBI2;
288 else if (strcmp(type, "pmic-arbiter") == 0)
289 ssbi->controller_type = MSM_SBI_CTRL_PMIC_ARBITER;
290 else {
291 dev_err(&pdev->dev, "Unknown qcom,controller-type\n");
292 return -EINVAL;
293 }
294
295 if (ssbi->controller_type == MSM_SBI_CTRL_PMIC_ARBITER) {
296 ssbi->read = ssbi_pa_read_bytes;
297 ssbi->write = ssbi_pa_write_bytes;
298 } else {
299 ssbi->read = ssbi_read_bytes;
300 ssbi->write = ssbi_write_bytes;
301 }
302
303 spin_lock_init(&ssbi->lock);
304
305 return devm_of_platform_populate(&pdev->dev);
306}
307
308static const struct of_device_id ssbi_match_table[] = {
309 { .compatible = "qcom,ssbi" },
310 {}
311};
312MODULE_DEVICE_TABLE(of, ssbi_match_table);
313
314static struct platform_driver ssbi_driver = {
315 .probe = ssbi_probe,
316 .driver = {
317 .name = "ssbi",
318 .of_match_table = ssbi_match_table,
319 },
320};
321module_platform_driver(ssbi_driver);
322
323MODULE_LICENSE("GPL v2");
324MODULE_VERSION("1.0");
325MODULE_ALIAS("platform:ssbi");
326MODULE_AUTHOR("Dima Zavin <dima@android.com>");