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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)
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)
52
53#define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000))
54
55struct 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
67static 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
73static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg)
74{
75 return readl(i2c_dev->regs + reg);
76}
77
78static 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
93static 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
108static 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
146static 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;
154 INIT_COMPLETION(i2c_dev->completion);
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
193static 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
209static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
210{
211 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
212}
213
214static const struct i2c_algorithm bcm2835_i2c_algo = {
215 .master_xfer = bcm2835_i2c_xfer,
216 .functionality = bcm2835_i2c_func,
217};
218
219static 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
274
275
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;
302
303 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
304
305 ret = i2c_add_adapter(adap);
306 if (ret)
307 free_irq(i2c_dev->irq, i2c_dev);
308
309 return ret;
310}
311
312static int bcm2835_i2c_remove(struct platform_device *pdev)
313{
314 struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
315
316 free_irq(i2c_dev->irq, i2c_dev);
317 i2c_del_adapter(&i2c_dev->adapter);
318
319 return 0;
320}
321
322static const struct of_device_id bcm2835_i2c_of_match[] = {
323 { .compatible = "brcm,bcm2835-i2c" },
324 {},
325};
326MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match);
327
328static struct platform_driver bcm2835_i2c_driver = {
329 .probe = bcm2835_i2c_probe,
330 .remove = bcm2835_i2c_remove,
331 .driver = {
332 .name = "i2c-bcm2835",
333 .owner = THIS_MODULE,
334 .of_match_table = bcm2835_i2c_of_match,
335 },
336};
337module_platform_driver(bcm2835_i2c_driver);
338
339MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
340MODULE_DESCRIPTION("BCM2835 I2C bus adapter");
341MODULE_LICENSE("GPL v2");
342MODULE_ALIAS("platform:i2c-bcm2835");
343
