source: src/linux/universal/linux-4.9/drivers/i2c/busses/i2c-bcm2835.c @ 31574

Last change on this file since 31574 was 31574, checked in by brainslayer, 7 weeks ago

kernel 4.9 update

File size: 8.8 KB
Line 
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_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
225/*
226 * This HW was reported to have problems with clock stretching:
227 * http://www.advamation.com/knowhow/raspberrypi/rpi-i2c-bug.html
228 * https://www.raspberrypi.org/forums/viewtopic.php?p=146272
229 */
230static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
231        .flags = I2C_AQ_NO_CLK_STRETCH,
232};
233
234static int bcm2835_i2c_probe(struct platform_device *pdev)
235{
236        struct bcm2835_i2c_dev *i2c_dev;
237        struct resource *mem, *irq;
238        u32 bus_clk_rate, divider;
239        int ret;
240        struct i2c_adapter *adap;
241
242        i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
243        if (!i2c_dev)
244                return -ENOMEM;
245        platform_set_drvdata(pdev, i2c_dev);
246        i2c_dev->dev = &pdev->dev;
247        init_completion(&i2c_dev->completion);
248
249        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
250        i2c_dev->regs = devm_ioremap_resource(&pdev->dev, mem);
251        if (IS_ERR(i2c_dev->regs))
252                return PTR_ERR(i2c_dev->regs);
253
254        i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
255        if (IS_ERR(i2c_dev->clk)) {
256                if (PTR_ERR(i2c_dev->clk) != -EPROBE_DEFER)
257                        dev_err(&pdev->dev, "Could not get clock\n");
258                return PTR_ERR(i2c_dev->clk);
259        }
260
261        ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
262                                   &bus_clk_rate);
263        if (ret < 0) {
264                dev_warn(&pdev->dev,
265                         "Could not read clock-frequency property\n");
266                bus_clk_rate = 100000;
267        }
268
269        divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate);
270        /*
271         * Per the datasheet, the register is always interpreted as an even
272         * number, by rounding down. In other words, the LSB is ignored. So,
273         * if the LSB is set, increment the divider to avoid any issue.
274         */
275        if (divider & 1)
276                divider++;
277        if ((divider < BCM2835_I2C_CDIV_MIN) ||
278            (divider > BCM2835_I2C_CDIV_MAX)) {
279                dev_err(&pdev->dev, "Invalid clock-frequency\n");
280                return -ENODEV;
281        }
282        bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);
283
284        irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
285        if (!irq) {
286                dev_err(&pdev->dev, "No IRQ resource\n");
287                return -ENODEV;
288        }
289        i2c_dev->irq = irq->start;
290
291        ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED,
292                          dev_name(&pdev->dev), i2c_dev);
293        if (ret) {
294                dev_err(&pdev->dev, "Could not request IRQ\n");
295                return -ENODEV;
296        }
297
298        adap = &i2c_dev->adapter;
299        i2c_set_adapdata(adap, i2c_dev);
300        adap->owner = THIS_MODULE;
301        adap->class = I2C_CLASS_DEPRECATED;
302        strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name));
303        adap->algo = &bcm2835_i2c_algo;
304        adap->dev.parent = &pdev->dev;
305        adap->dev.of_node = pdev->dev.of_node;
306        adap->quirks = &bcm2835_i2c_quirks;
307
308        bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
309
310        ret = i2c_add_adapter(adap);
311        if (ret)
312                free_irq(i2c_dev->irq, i2c_dev);
313
314        return ret;
315}
316
317static int bcm2835_i2c_remove(struct platform_device *pdev)
318{
319        struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
320
321        free_irq(i2c_dev->irq, i2c_dev);
322        i2c_del_adapter(&i2c_dev->adapter);
323
324        return 0;
325}
326
327static const struct of_device_id bcm2835_i2c_of_match[] = {
328        { .compatible = "brcm,bcm2835-i2c" },
329        {},
330};
331MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match);
332
333static struct platform_driver bcm2835_i2c_driver = {
334        .probe          = bcm2835_i2c_probe,
335        .remove         = bcm2835_i2c_remove,
336        .driver         = {
337                .name   = "i2c-bcm2835",
338                .of_match_table = bcm2835_i2c_of_match,
339        },
340};
341module_platform_driver(bcm2835_i2c_driver);
342
343MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
344MODULE_DESCRIPTION("BCM2835 I2C bus adapter");
345MODULE_LICENSE("GPL v2");
346MODULE_ALIAS("platform:i2c-bcm2835");
Note: See TracBrowser for help on using the repository browser.