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f3b54b9a SW |
1 | /* |
2 | * BCM2835 master mode driver | |
3 | * | |
4 | * This software is licensed under the terms of the GNU General Public | |
5 | * License version 2, as published by the Free Software Foundation, and | |
6 | * may be copied, distributed, and modified under those terms. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, | |
9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
11 | * GNU General Public License for more details. | |
12 | */ | |
13 | ||
14 | #include <linux/clk.h> | |
15 | #include <linux/completion.h> | |
16 | #include <linux/err.h> | |
17 | #include <linux/i2c.h> | |
18 | #include <linux/interrupt.h> | |
19 | #include <linux/io.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/platform_device.h> | |
22 | #include <linux/slab.h> | |
23 | ||
24 | #define BCM2835_I2C_C 0x0 | |
25 | #define BCM2835_I2C_S 0x4 | |
26 | #define BCM2835_I2C_DLEN 0x8 | |
27 | #define BCM2835_I2C_A 0xc | |
28 | #define BCM2835_I2C_FIFO 0x10 | |
29 | #define BCM2835_I2C_DIV 0x14 | |
30 | #define BCM2835_I2C_DEL 0x18 | |
31 | #define BCM2835_I2C_CLKT 0x1c | |
32 | ||
33 | #define BCM2835_I2C_C_READ BIT(0) | |
34 | #define BCM2835_I2C_C_CLEAR BIT(4) /* bits 4 and 5 both clear */ | |
35 | #define BCM2835_I2C_C_ST BIT(7) | |
36 | #define BCM2835_I2C_C_INTD BIT(8) | |
37 | #define BCM2835_I2C_C_INTT BIT(9) | |
38 | #define BCM2835_I2C_C_INTR BIT(10) | |
39 | #define BCM2835_I2C_C_I2CEN BIT(15) | |
40 | ||
41 | #define BCM2835_I2C_S_TA BIT(0) | |
42 | #define BCM2835_I2C_S_DONE BIT(1) | |
43 | #define BCM2835_I2C_S_TXW BIT(2) | |
44 | #define BCM2835_I2C_S_RXR BIT(3) | |
45 | #define BCM2835_I2C_S_TXD BIT(4) | |
46 | #define BCM2835_I2C_S_RXD BIT(5) | |
47 | #define BCM2835_I2C_S_TXE BIT(6) | |
48 | #define BCM2835_I2C_S_RXF BIT(7) | |
49 | #define BCM2835_I2C_S_ERR BIT(8) | |
50 | #define BCM2835_I2C_S_CLKT BIT(9) | |
51 | #define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */ | |
52 | ||
53 | #define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000)) | |
54 | ||
55 | struct bcm2835_i2c_dev { | |
56 | struct device *dev; | |
57 | void __iomem *regs; | |
58 | struct clk *clk; | |
59 | int irq; | |
60 | struct i2c_adapter adapter; | |
61 | struct completion completion; | |
62 | u32 msg_err; | |
63 | u8 *msg_buf; | |
64 | size_t msg_buf_remaining; | |
65 | }; | |
66 | ||
67 | static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev, | |
68 | u32 reg, u32 val) | |
69 | { | |
70 | writel(val, i2c_dev->regs + reg); | |
71 | } | |
72 | ||
73 | static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg) | |
74 | { | |
75 | return readl(i2c_dev->regs + reg); | |
76 | } | |
77 | ||
78 | static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev) | |
79 | { | |
80 | u32 val; | |
81 | ||
82 | while (i2c_dev->msg_buf_remaining) { | |
83 | val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); | |
84 | if (!(val & BCM2835_I2C_S_TXD)) | |
85 | break; | |
86 | bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_FIFO, | |
87 | *i2c_dev->msg_buf); | |
88 | i2c_dev->msg_buf++; | |
89 | i2c_dev->msg_buf_remaining--; | |
90 | } | |
91 | } | |
92 | ||
93 | static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev) | |
94 | { | |
95 | u32 val; | |
96 | ||
97 | while (i2c_dev->msg_buf_remaining) { | |
98 | val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); | |
99 | if (!(val & BCM2835_I2C_S_RXD)) | |
100 | break; | |
101 | *i2c_dev->msg_buf = bcm2835_i2c_readl(i2c_dev, | |
102 | BCM2835_I2C_FIFO); | |
103 | i2c_dev->msg_buf++; | |
104 | i2c_dev->msg_buf_remaining--; | |
105 | } | |
106 | } | |
107 | ||
108 | static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) | |
109 | { | |
110 | struct bcm2835_i2c_dev *i2c_dev = data; | |
111 | u32 val, err; | |
112 | ||
113 | val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); | |
114 | bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val); | |
115 | ||
116 | err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR); | |
117 | if (err) { | |
118 | i2c_dev->msg_err = err; | |
119 | complete(&i2c_dev->completion); | |
120 | return IRQ_HANDLED; | |
121 | } | |
122 | ||
123 | if (val & BCM2835_I2C_S_RXD) { | |
124 | bcm2835_drain_rxfifo(i2c_dev); | |
125 | if (!(val & BCM2835_I2C_S_DONE)) | |
126 | return IRQ_HANDLED; | |
127 | } | |
128 | ||
129 | if (val & BCM2835_I2C_S_DONE) { | |
130 | if (i2c_dev->msg_buf_remaining) | |
131 | i2c_dev->msg_err = BCM2835_I2C_S_LEN; | |
132 | else | |
133 | i2c_dev->msg_err = 0; | |
134 | complete(&i2c_dev->completion); | |
135 | return IRQ_HANDLED; | |
136 | } | |
137 | ||
138 | if (val & BCM2835_I2C_S_TXD) { | |
139 | bcm2835_fill_txfifo(i2c_dev); | |
140 | return IRQ_HANDLED; | |
141 | } | |
142 | ||
143 | return IRQ_NONE; | |
144 | } | |
145 | ||
146 | static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev, | |
147 | struct i2c_msg *msg) | |
148 | { | |
149 | u32 c; | |
150 | int time_left; | |
151 | ||
152 | i2c_dev->msg_buf = msg->buf; | |
153 | i2c_dev->msg_buf_remaining = msg->len; | |
16735d02 | 154 | reinit_completion(&i2c_dev->completion); |
f3b54b9a SW |
155 | |
156 | bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); | |
157 | ||
158 | if (msg->flags & I2C_M_RD) { | |
159 | c = BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR; | |
160 | } else { | |
161 | c = BCM2835_I2C_C_INTT; | |
162 | bcm2835_fill_txfifo(i2c_dev); | |
163 | } | |
164 | c |= BCM2835_I2C_C_ST | BCM2835_I2C_C_INTD | BCM2835_I2C_C_I2CEN; | |
165 | ||
166 | bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr); | |
167 | bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len); | |
168 | bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c); | |
169 | ||
170 | time_left = wait_for_completion_timeout(&i2c_dev->completion, | |
171 | BCM2835_I2C_TIMEOUT); | |
172 | bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); | |
173 | if (!time_left) { | |
174 | dev_err(i2c_dev->dev, "i2c transfer timed out\n"); | |
175 | return -ETIMEDOUT; | |
176 | } | |
177 | ||
178 | if (likely(!i2c_dev->msg_err)) | |
179 | return 0; | |
180 | ||
181 | if ((i2c_dev->msg_err & BCM2835_I2C_S_ERR) && | |
182 | (msg->flags & I2C_M_IGNORE_NAK)) | |
183 | return 0; | |
184 | ||
185 | dev_err(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err); | |
186 | ||
187 | if (i2c_dev->msg_err & BCM2835_I2C_S_ERR) | |
188 | return -EREMOTEIO; | |
189 | else | |
190 | return -EIO; | |
191 | } | |
192 | ||
193 | static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], | |
194 | int num) | |
195 | { | |
196 | struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap); | |
197 | int i; | |
198 | int ret = 0; | |
199 | ||
200 | for (i = 0; i < num; i++) { | |
201 | ret = bcm2835_i2c_xfer_msg(i2c_dev, &msgs[i]); | |
202 | if (ret) | |
203 | break; | |
204 | } | |
205 | ||
206 | return ret ?: i; | |
207 | } | |
208 | ||
209 | static u32 bcm2835_i2c_func(struct i2c_adapter *adap) | |
210 | { | |
211 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; | |
212 | } | |
213 | ||
214 | static const struct i2c_algorithm bcm2835_i2c_algo = { | |
215 | .master_xfer = bcm2835_i2c_xfer, | |
216 | .functionality = bcm2835_i2c_func, | |
217 | }; | |
218 | ||
219 | static int bcm2835_i2c_probe(struct platform_device *pdev) | |
220 | { | |
221 | struct bcm2835_i2c_dev *i2c_dev; | |
222 | struct resource *mem, *requested, *irq; | |
223 | u32 bus_clk_rate, divider; | |
224 | int ret; | |
225 | struct i2c_adapter *adap; | |
226 | ||
227 | i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL); | |
228 | if (!i2c_dev) { | |
229 | dev_err(&pdev->dev, "Cannot allocate i2c_dev\n"); | |
230 | return -ENOMEM; | |
231 | } | |
232 | platform_set_drvdata(pdev, i2c_dev); | |
233 | i2c_dev->dev = &pdev->dev; | |
234 | init_completion(&i2c_dev->completion); | |
235 | ||
236 | mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
237 | if (!mem) { | |
238 | dev_err(&pdev->dev, "No mem resource\n"); | |
239 | return -ENODEV; | |
240 | } | |
241 | ||
242 | requested = devm_request_mem_region(&pdev->dev, mem->start, | |
243 | resource_size(mem), | |
244 | dev_name(&pdev->dev)); | |
245 | if (!requested) { | |
246 | dev_err(&pdev->dev, "Could not claim register region\n"); | |
247 | return -EBUSY; | |
248 | } | |
249 | ||
250 | i2c_dev->regs = devm_ioremap(&pdev->dev, mem->start, | |
251 | resource_size(mem)); | |
252 | if (!i2c_dev->regs) { | |
253 | dev_err(&pdev->dev, "Could not map registers\n"); | |
254 | return -ENOMEM; | |
255 | } | |
256 | ||
257 | i2c_dev->clk = devm_clk_get(&pdev->dev, NULL); | |
258 | if (IS_ERR(i2c_dev->clk)) { | |
259 | dev_err(&pdev->dev, "Could not get clock\n"); | |
260 | return PTR_ERR(i2c_dev->clk); | |
261 | } | |
262 | ||
263 | ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", | |
264 | &bus_clk_rate); | |
265 | if (ret < 0) { | |
266 | dev_warn(&pdev->dev, | |
267 | "Could not read clock-frequency property\n"); | |
268 | bus_clk_rate = 100000; | |
269 | } | |
270 | ||
271 | divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate); | |
272 | /* | |
273 | * Per the datasheet, the register is always interpreted as an even | |
274 | * number, by rounding down. In other words, the LSB is ignored. So, | |
275 | * if the LSB is set, increment the divider to avoid any issue. | |
276 | */ | |
277 | if (divider & 1) | |
278 | divider++; | |
279 | bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); | |
280 | ||
281 | irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); | |
282 | if (!irq) { | |
283 | dev_err(&pdev->dev, "No IRQ resource\n"); | |
284 | return -ENODEV; | |
285 | } | |
286 | i2c_dev->irq = irq->start; | |
287 | ||
288 | ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED, | |
289 | dev_name(&pdev->dev), i2c_dev); | |
290 | if (ret) { | |
291 | dev_err(&pdev->dev, "Could not request IRQ\n"); | |
292 | return -ENODEV; | |
293 | } | |
294 | ||
295 | adap = &i2c_dev->adapter; | |
296 | i2c_set_adapdata(adap, i2c_dev); | |
297 | adap->owner = THIS_MODULE; | |
298 | adap->class = I2C_CLASS_HWMON; | |
299 | strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name)); | |
300 | adap->algo = &bcm2835_i2c_algo; | |
301 | adap->dev.parent = &pdev->dev; | |
07a27a00 | 302 | adap->dev.of_node = pdev->dev.of_node; |
f3b54b9a SW |
303 | |
304 | bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0); | |
305 | ||
306 | ret = i2c_add_adapter(adap); | |
307 | if (ret) | |
308 | free_irq(i2c_dev->irq, i2c_dev); | |
309 | ||
310 | return ret; | |
311 | } | |
312 | ||
313 | static int bcm2835_i2c_remove(struct platform_device *pdev) | |
314 | { | |
315 | struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev); | |
316 | ||
317 | free_irq(i2c_dev->irq, i2c_dev); | |
318 | i2c_del_adapter(&i2c_dev->adapter); | |
319 | ||
320 | return 0; | |
321 | } | |
322 | ||
323 | static const struct of_device_id bcm2835_i2c_of_match[] = { | |
324 | { .compatible = "brcm,bcm2835-i2c" }, | |
325 | {}, | |
326 | }; | |
327 | MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match); | |
328 | ||
329 | static struct platform_driver bcm2835_i2c_driver = { | |
330 | .probe = bcm2835_i2c_probe, | |
331 | .remove = bcm2835_i2c_remove, | |
332 | .driver = { | |
333 | .name = "i2c-bcm2835", | |
334 | .owner = THIS_MODULE, | |
335 | .of_match_table = bcm2835_i2c_of_match, | |
336 | }, | |
337 | }; | |
338 | module_platform_driver(bcm2835_i2c_driver); | |
339 | ||
340 | MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>"); | |
341 | MODULE_DESCRIPTION("BCM2835 I2C bus adapter"); | |
342 | MODULE_LICENSE("GPL v2"); | |
343 | MODULE_ALIAS("platform:i2c-bcm2835"); |