source: src/linux/universal/linux-4.9/drivers/i2c/busses/i2c-bcm2835.c @ 31884

Last change on this file since 31884 was 31884, checked in by brainslayer, 6 weeks ago

update kernels

File size: 9.0 KB
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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        struct i2c_msg *curr_msg;
68        u32 msg_err;
69        u8 *msg_buf;
70        size_t msg_buf_remaining;
71};
72
73static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev,
74                                      u32 reg, u32 val)
75{
76        writel(val, i2c_dev->regs + reg);
77}
78
79static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg)
80{
81        return readl(i2c_dev->regs + reg);
82}
83
84static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev)
85{
86        u32 val;
87
88        while (i2c_dev->msg_buf_remaining) {
89                val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
90                if (!(val & BCM2835_I2C_S_TXD))
91                        break;
92                bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_FIFO,
93                                   *i2c_dev->msg_buf);
94                i2c_dev->msg_buf++;
95                i2c_dev->msg_buf_remaining--;
96        }
97}
98
99static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev)
100{
101        u32 val;
102
103        while (i2c_dev->msg_buf_remaining) {
104                val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
105                if (!(val & BCM2835_I2C_S_RXD))
106                        break;
107                *i2c_dev->msg_buf = bcm2835_i2c_readl(i2c_dev,
108                                                      BCM2835_I2C_FIFO);
109                i2c_dev->msg_buf++;
110                i2c_dev->msg_buf_remaining--;
111        }
112}
113
114static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data)
115{
116        struct bcm2835_i2c_dev *i2c_dev = data;
117        u32 val, err;
118
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);
122
123        err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
124        if (err) {
125                i2c_dev->msg_err = err;
126                complete(&i2c_dev->completion);
127                return IRQ_HANDLED;
128        }
129
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);
134                }
135
136                if ((val & BCM2835_I2C_S_RXD) || 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_TXW) {
145                bcm2835_fill_txfifo(i2c_dev);
146                return IRQ_HANDLED;
147        }
148
149        if (val & BCM2835_I2C_S_RXR) {
150                bcm2835_drain_rxfifo(i2c_dev);
151                return IRQ_HANDLED;
152        }
153
154        return IRQ_NONE;
155}
156
157static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev,
158                                struct i2c_msg *msg)
159{
160        u32 c;
161        unsigned long time_left;
162
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);
167
168        bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR);
169
170        if (msg->flags & I2C_M_RD) {
171                c = BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR;
172        } else {
173                c = BCM2835_I2C_C_INTT;
174                bcm2835_fill_txfifo(i2c_dev);
175        }
176        c |= BCM2835_I2C_C_ST | BCM2835_I2C_C_INTD | BCM2835_I2C_C_I2CEN;
177
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);
181
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);
185        if (!time_left) {
186                dev_err(i2c_dev->dev, "i2c transfer timed out\n");
187                return -ETIMEDOUT;
188        }
189
190        if (likely(!i2c_dev->msg_err))
191                return 0;
192
193        if ((i2c_dev->msg_err & BCM2835_I2C_S_ERR) &&
194            (msg->flags & I2C_M_IGNORE_NAK))
195                return 0;
196
197        dev_err(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err);
198
199        if (i2c_dev->msg_err & BCM2835_I2C_S_ERR)
200                return -EREMOTEIO;
201        else
202                return -EIO;
203}
204
205static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
206                            int num)
207{
208        struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
209        int i;
210        int ret = 0;
211
212        for (i = 0; i < num; i++) {
213                ret = bcm2835_i2c_xfer_msg(i2c_dev, &msgs[i]);
214                if (ret)
215                        break;
216        }
217
218        return ret ?: i;
219}
220
221static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
222{
223        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
224}
225
226static const struct i2c_algorithm bcm2835_i2c_algo = {
227        .master_xfer    = bcm2835_i2c_xfer,
228        .functionality  = bcm2835_i2c_func,
229};
230
231/*
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
235 */
236static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
237        .flags = I2C_AQ_NO_CLK_STRETCH,
238};
239
240static int bcm2835_i2c_probe(struct platform_device *pdev)
241{
242        struct bcm2835_i2c_dev *i2c_dev;
243        struct resource *mem, *irq;
244        u32 bus_clk_rate, divider;
245        int ret;
246        struct i2c_adapter *adap;
247
248        i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
249        if (!i2c_dev)
250                return -ENOMEM;
251        platform_set_drvdata(pdev, i2c_dev);
252        i2c_dev->dev = &pdev->dev;
253        init_completion(&i2c_dev->completion);
254
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);
259
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);
265        }
266
267        ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
268                                   &bus_clk_rate);
269        if (ret < 0) {
270                dev_warn(&pdev->dev,
271                         "Could not read clock-frequency property\n");
272                bus_clk_rate = 100000;
273        }
274
275        divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate);
276        /*
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.
280         */
281        if (divider & 1)
282                divider++;
283        if ((divider < BCM2835_I2C_CDIV_MIN) ||
284            (divider > BCM2835_I2C_CDIV_MAX)) {
285                dev_err(&pdev->dev, "Invalid clock-frequency\n");
286                return -ENODEV;
287        }
288        bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);
289
290        irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
291        if (!irq) {
292                dev_err(&pdev->dev, "No IRQ resource\n");
293                return -ENODEV;
294        }
295        i2c_dev->irq = irq->start;
296
297        ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED,
298                          dev_name(&pdev->dev), i2c_dev);
299        if (ret) {
300                dev_err(&pdev->dev, "Could not request IRQ\n");
301                return -ENODEV;
302        }
303
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;
313
314        bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
315
316        ret = i2c_add_adapter(adap);
317        if (ret)
318                free_irq(i2c_dev->irq, i2c_dev);
319
320        return ret;
321}
322
323static int bcm2835_i2c_remove(struct platform_device *pdev)
324{
325        struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
326
327        free_irq(i2c_dev->irq, i2c_dev);
328        i2c_del_adapter(&i2c_dev->adapter);
329
330        return 0;
331}
332
333static const struct of_device_id bcm2835_i2c_of_match[] = {
334        { .compatible = "brcm,bcm2835-i2c" },
335        {},
336};
337MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match);
338
339static struct platform_driver bcm2835_i2c_driver = {
340        .probe          = bcm2835_i2c_probe,
341        .remove         = bcm2835_i2c_remove,
342        .driver         = {
343                .name   = "i2c-bcm2835",
344                .of_match_table = bcm2835_i2c_of_match,
345        },
346};
347module_platform_driver(bcm2835_i2c_driver);
348
349MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>");
350MODULE_DESCRIPTION("BCM2835 I2C bus adapter");
351MODULE_LICENSE("GPL v2");
352MODULE_ALIAS("platform:i2c-bcm2835");
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