2 * BCM2835 master mode driver
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.
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.
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>
20 #include <linux/module.h>
21 #include <linux/platform_device.h>
22 #include <linux/slab.h>
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
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)
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 */
53 #define BCM2835_I2C_BITMSK_S 0x03FF
55 #define BCM2835_I2C_CDIV_MIN 0x0002
56 #define BCM2835_I2C_CDIV_MAX 0xFFFE
58 #define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000))
60 struct bcm2835_i2c_dev {
65 struct i2c_adapter adapter;
66 struct completion completion;
67 struct i2c_msg *curr_msg;
70 size_t msg_buf_remaining;
73 static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev,
76 writel(val, i2c_dev->regs + reg);
79 static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg)
81 return readl(i2c_dev->regs + reg);
84 static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev)
88 while (i2c_dev->msg_buf_remaining) {
89 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
90 if (!(val & BCM2835_I2C_S_TXD))
92 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_FIFO,
95 i2c_dev->msg_buf_remaining--;
99 static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev)
103 while (i2c_dev->msg_buf_remaining) {
104 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
105 if (!(val & BCM2835_I2C_S_RXD))
107 *i2c_dev->msg_buf = bcm2835_i2c_readl(i2c_dev,
110 i2c_dev->msg_buf_remaining--;
114 static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data)
116 struct bcm2835_i2c_dev *i2c_dev = data;
119 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
120 val &= BCM2835_I2C_BITMSK_S;
121 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val);
123 err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
125 i2c_dev->msg_err = err;
126 complete(&i2c_dev->completion);
130 if (val & BCM2835_I2C_S_DONE) {
131 if (i2c_dev->curr_msg->flags & I2C_M_RD) {
132 bcm2835_drain_rxfifo(i2c_dev);
133 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
136 if ((val & BCM2835_I2C_S_RXD) || i2c_dev->msg_buf_remaining)
137 i2c_dev->msg_err = BCM2835_I2C_S_LEN;
139 i2c_dev->msg_err = 0;
140 complete(&i2c_dev->completion);
144 if (val & BCM2835_I2C_S_TXW) {
145 bcm2835_fill_txfifo(i2c_dev);
149 if (val & BCM2835_I2C_S_RXR) {
150 bcm2835_drain_rxfifo(i2c_dev);
157 static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev,
161 unsigned long time_left;
163 i2c_dev->curr_msg = msg;
164 i2c_dev->msg_buf = msg->buf;
165 i2c_dev->msg_buf_remaining = msg->len;
166 reinit_completion(&i2c_dev->completion);
168 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR);
170 if (msg->flags & I2C_M_RD) {
171 c = BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR;
173 c = BCM2835_I2C_C_INTT;
174 bcm2835_fill_txfifo(i2c_dev);
176 c |= BCM2835_I2C_C_ST | BCM2835_I2C_C_INTD | BCM2835_I2C_C_I2CEN;
178 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr);
179 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len);
180 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c);
182 time_left = wait_for_completion_timeout(&i2c_dev->completion,
183 BCM2835_I2C_TIMEOUT);
184 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR);
186 dev_err(i2c_dev->dev, "i2c transfer timed out\n");
190 if (likely(!i2c_dev->msg_err))
193 if ((i2c_dev->msg_err & BCM2835_I2C_S_ERR) &&
194 (msg->flags & I2C_M_IGNORE_NAK))
197 dev_err(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err);
199 if (i2c_dev->msg_err & BCM2835_I2C_S_ERR)
205 static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
208 struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
212 for (i = 0; i < num; i++) {
213 ret = bcm2835_i2c_xfer_msg(i2c_dev, &msgs[i]);
221 static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
223 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
226 static const struct i2c_algorithm bcm2835_i2c_algo = {
227 .master_xfer = bcm2835_i2c_xfer,
228 .functionality = bcm2835_i2c_func,
232 * This HW was reported to have problems with clock stretching:
233 * http://www.advamation.com/knowhow/raspberrypi/rpi-i2c-bug.html
234 * https://www.raspberrypi.org/forums/viewtopic.php?p=146272
236 static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
237 .flags = I2C_AQ_NO_CLK_STRETCH,
240 static int bcm2835_i2c_probe(struct platform_device *pdev)
242 struct bcm2835_i2c_dev *i2c_dev;
243 struct resource *mem, *irq;
244 u32 bus_clk_rate, divider;
246 struct i2c_adapter *adap;
248 i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
251 platform_set_drvdata(pdev, i2c_dev);
252 i2c_dev->dev = &pdev->dev;
253 init_completion(&i2c_dev->completion);
255 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
256 i2c_dev->regs = devm_ioremap_resource(&pdev->dev, mem);
257 if (IS_ERR(i2c_dev->regs))
258 return PTR_ERR(i2c_dev->regs);
260 i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
261 if (IS_ERR(i2c_dev->clk)) {
262 if (PTR_ERR(i2c_dev->clk) != -EPROBE_DEFER)
263 dev_err(&pdev->dev, "Could not get clock\n");
264 return PTR_ERR(i2c_dev->clk);
267 ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
271 "Could not read clock-frequency property\n");
272 bus_clk_rate = 100000;
275 divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate);
277 * Per the datasheet, the register is always interpreted as an even
278 * number, by rounding down. In other words, the LSB is ignored. So,
279 * if the LSB is set, increment the divider to avoid any issue.
283 if ((divider < BCM2835_I2C_CDIV_MIN) ||
284 (divider > BCM2835_I2C_CDIV_MAX)) {
285 dev_err(&pdev->dev, "Invalid clock-frequency\n");
288 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);
290 irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
292 dev_err(&pdev->dev, "No IRQ resource\n");
295 i2c_dev->irq = irq->start;
297 ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED,
298 dev_name(&pdev->dev), i2c_dev);
300 dev_err(&pdev->dev, "Could not request IRQ\n");
304 adap = &i2c_dev->adapter;
305 i2c_set_adapdata(adap, i2c_dev);
306 adap->owner = THIS_MODULE;
307 adap->class = I2C_CLASS_DEPRECATED;
308 strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name));
309 adap->algo = &bcm2835_i2c_algo;
310 adap->dev.parent = &pdev->dev;
311 adap->dev.of_node = pdev->dev.of_node;
312 adap->quirks = &bcm2835_i2c_quirks;
314 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
316 ret = i2c_add_adapter(adap);
318 free_irq(i2c_dev->irq, i2c_dev);
323 static int bcm2835_i2c_remove(struct platform_device *pdev)
325 struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
327 free_irq(i2c_dev->irq, i2c_dev);
328 i2c_del_adapter(&i2c_dev->adapter);
333 static const struct of_device_id bcm2835_i2c_of_match[] = {
334 { .compatible = "brcm,bcm2835-i2c" },
337 MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match);
339 static struct platform_driver bcm2835_i2c_driver = {
340 .probe = bcm2835_i2c_probe,
341 .remove = bcm2835_i2c_remove,
343 .name = "i2c-bcm2835",
344 .of_match_table = bcm2835_i2c_of_match,
347 module_platform_driver(bcm2835_i2c_driver);
349 MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
350 MODULE_DESCRIPTION("BCM2835 I2C bus adapter");
351 MODULE_LICENSE("GPL v2");
352 MODULE_ALIAS("platform:i2c-bcm2835");