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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_BITMSK_S 0x03FF
54
55#define BCM2835_I2C_CDIV_MIN 0x0002
56#define BCM2835_I2C_CDIV_MAX 0xFFFE
57
58#define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000))
59
60struct bcm2835_i2c_dev {
61 struct device *dev;
62 void __iomem *regs;
63 struct clk *clk;
64 int irq;
65 struct i2c_adapter adapter;
66 struct completion completion;
67 u32 msg_err;
68 u8 *msg_buf;
69 size_t msg_buf_remaining;
70};
71
72static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev,
73 u32 reg, u32 val)
74{
75 writel(val, i2c_dev->regs + reg);
76}
77
78static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg)
79{
80 return readl(i2c_dev->regs + reg);
81}
82
83static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev)
84{
85 u32 val;
86
87 while (i2c_dev->msg_buf_remaining) {
88 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
89 if (!(val & BCM2835_I2C_S_TXD))
90 break;
91 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_FIFO,
92 *i2c_dev->msg_buf);
93 i2c_dev->msg_buf++;
94 i2c_dev->msg_buf_remaining--;
95 }
96}
97
98static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev)
99{
100 u32 val;
101
102 while (i2c_dev->msg_buf_remaining) {
103 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
104 if (!(val & BCM2835_I2C_S_RXD))
105 break;
106 *i2c_dev->msg_buf = bcm2835_i2c_readl(i2c_dev,
107 BCM2835_I2C_FIFO);
108 i2c_dev->msg_buf++;
109 i2c_dev->msg_buf_remaining--;
110 }
111}
112
113static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data)
114{
115 struct bcm2835_i2c_dev *i2c_dev = data;
116 u32 val, err;
117
118 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
119 val &= BCM2835_I2C_BITMSK_S;
120 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val);
121
122 err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
123 if (err) {
124 i2c_dev->msg_err = err;
125 complete(&i2c_dev->completion);
126 return IRQ_HANDLED;
127 }
128
129 if (val & BCM2835_I2C_S_RXD) {
130 bcm2835_drain_rxfifo(i2c_dev);
131 if (!(val & BCM2835_I2C_S_DONE))
132 return IRQ_HANDLED;
133 }
134
135 if (val & BCM2835_I2C_S_DONE) {
136 if (i2c_dev->msg_buf_remaining)
137 i2c_dev->msg_err = BCM2835_I2C_S_LEN;
138 else
139 i2c_dev->msg_err = 0;
140 complete(&i2c_dev->completion);
141 return IRQ_HANDLED;
142 }
143
144 if (val & BCM2835_I2C_S_TXD) {
145 bcm2835_fill_txfifo(i2c_dev);
146 return IRQ_HANDLED;
147 }
148
149 return IRQ_NONE;
150}
151
152static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev,
153 struct i2c_msg *msg)
154{
155 u32 c;
156 unsigned long time_left;
157
158 i2c_dev->msg_buf = msg->buf;
159 i2c_dev->msg_buf_remaining = msg->len;
160 reinit_completion(&i2c_dev->completion);
161
162 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR);
163
164 if (msg->flags & I2C_M_RD) {
165 c = BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR;
166 } else {
167 c = BCM2835_I2C_C_INTT;
168 bcm2835_fill_txfifo(i2c_dev);
169 }
170 c |= BCM2835_I2C_C_ST | BCM2835_I2C_C_INTD | BCM2835_I2C_C_I2CEN;
171
172 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr);
173 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len);
174 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c);
175
176 time_left = wait_for_completion_timeout(&i2c_dev->completion,
177 BCM2835_I2C_TIMEOUT);
178 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR);
179 if (!time_left) {
180 dev_err(i2c_dev->dev, "i2c transfer timed out\n");
181 return -ETIMEDOUT;
182 }
183
184 if (likely(!i2c_dev->msg_err))
185 return 0;
186
187 if ((i2c_dev->msg_err & BCM2835_I2C_S_ERR) &&
188 (msg->flags & I2C_M_IGNORE_NAK))
189 return 0;
190
191 dev_err(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err);
192
193 if (i2c_dev->msg_err & BCM2835_I2C_S_ERR)
194 return -EREMOTEIO;
195 else
196 return -EIO;
197}
198
199static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
200 int num)
201{
202 struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
203 int i;
204 int ret = 0;
205
206 for (i = 0; i < num; i++) {
207 ret = bcm2835_i2c_xfer_msg(i2c_dev, &msgs[i]);
208 if (ret)
209 break;
210 }
211
212 return ret ?: i;
213}
214
215static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
216{
217 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
218}
219
220static const struct i2c_algorithm bcm2835_i2c_algo = {
221 .master_xfer = bcm2835_i2c_xfer,
222 .functionality = bcm2835_i2c_func,
223};
224
225static int bcm2835_i2c_probe(struct platform_device *pdev)
226{
227 struct bcm2835_i2c_dev *i2c_dev;
228 struct resource *mem, *irq;
229 u32 bus_clk_rate, divider;
230 int ret;
231 struct i2c_adapter *adap;
232
233 i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
234 if (!i2c_dev)
235 return -ENOMEM;
236 platform_set_drvdata(pdev, i2c_dev);
237 i2c_dev->dev = &pdev->dev;
238 init_completion(&i2c_dev->completion);
239
240 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
241 i2c_dev->regs = devm_ioremap_resource(&pdev->dev, mem);
242 if (IS_ERR(i2c_dev->regs))
243 return PTR_ERR(i2c_dev->regs);
244
245 i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
246 if (IS_ERR(i2c_dev->clk)) {
247 dev_err(&pdev->dev, "Could not get clock\n");
248 return PTR_ERR(i2c_dev->clk);
249 }
250
251 ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
252 &bus_clk_rate);
253 if (ret < 0) {
254 dev_warn(&pdev->dev,
255 "Could not read clock-frequency property\n");
256 bus_clk_rate = 100000;
257 }
258
259 divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate);
260
261
262
263
264
265 if (divider & 1)
266 divider++;
267 if ((divider < BCM2835_I2C_CDIV_MIN) ||
268 (divider > BCM2835_I2C_CDIV_MAX)) {
269 dev_err(&pdev->dev, "Invalid clock-frequency\n");
270 return -ENODEV;
271 }
272 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);
273
274 irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
275 if (!irq) {
276 dev_err(&pdev->dev, "No IRQ resource\n");
277 return -ENODEV;
278 }
279 i2c_dev->irq = irq->start;
280
281 ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED,
282 dev_name(&pdev->dev), i2c_dev);
283 if (ret) {
284 dev_err(&pdev->dev, "Could not request IRQ\n");
285 return -ENODEV;
286 }
287
288 adap = &i2c_dev->adapter;
289 i2c_set_adapdata(adap, i2c_dev);
290 adap->owner = THIS_MODULE;
291 adap->class = I2C_CLASS_DEPRECATED;
292 strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name));
293 adap->algo = &bcm2835_i2c_algo;
294 adap->dev.parent = &pdev->dev;
295 adap->dev.of_node = pdev->dev.of_node;
296
297 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
298
299 ret = i2c_add_adapter(adap);
300 if (ret)
301 free_irq(i2c_dev->irq, i2c_dev);
302
303 return ret;
304}
305
306static int bcm2835_i2c_remove(struct platform_device *pdev)
307{
308 struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
309
310 free_irq(i2c_dev->irq, i2c_dev);
311 i2c_del_adapter(&i2c_dev->adapter);
312
313 return 0;
314}
315
316static const struct of_device_id bcm2835_i2c_of_match[] = {
317 { .compatible = "brcm,bcm2835-i2c" },
318 {},
319};
320MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match);
321
322static struct platform_driver bcm2835_i2c_driver = {
323 .probe = bcm2835_i2c_probe,
324 .remove = bcm2835_i2c_remove,
325 .driver = {
326 .name = "i2c-bcm2835",
327 .of_match_table = bcm2835_i2c_of_match,
328 },
329};
330module_platform_driver(bcm2835_i2c_driver);
331
332MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
333MODULE_DESCRIPTION("BCM2835 I2C bus adapter");
334MODULE_LICENSE("GPL v2");
335MODULE_ALIAS("platform:i2c-bcm2835");
336
