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813e30e9 AV |
1 | /* |
2 | i2c Support for Atmel's AT91 Two-Wire Interface (TWI) | |
3 | ||
4 | Copyright (C) 2004 Rick Bronson | |
5 | Converted to 2.6 by Andrew Victor <andrew@sanpeople.com> | |
6 | ||
7 | Borrowed heavily from original work by: | |
8 | Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com> | |
9 | ||
10 | This program is free software; you can redistribute it and/or modify | |
11 | it under the terms of the GNU General Public License as published by | |
12 | the Free Software Foundation; either version 2 of the License, or | |
13 | (at your option) any later version. | |
14 | */ | |
15 | ||
16 | #include <linux/module.h> | |
813e30e9 | 17 | #include <linux/kernel.h> |
c91e23c6 | 18 | #include <linux/err.h> |
813e30e9 | 19 | #include <linux/slab.h> |
813e30e9 AV |
20 | #include <linux/types.h> |
21 | #include <linux/delay.h> | |
22 | #include <linux/i2c.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/clk.h> | |
25 | #include <linux/platform_device.h> | |
21782180 | 26 | #include <linux/io.h> |
813e30e9 | 27 | |
a09e64fb RK |
28 | #include <mach/at91_twi.h> |
29 | #include <mach/board.h> | |
30 | #include <mach/cpu.h> | |
813e30e9 AV |
31 | |
32 | #define TWI_CLOCK 100000 /* Hz. max 400 Kbits/sec */ | |
33 | ||
34 | ||
35 | static struct clk *twi_clk; | |
36 | static void __iomem *twi_base; | |
37 | ||
38 | #define at91_twi_read(reg) __raw_readl(twi_base + (reg)) | |
39 | #define at91_twi_write(reg, val) __raw_writel((val), twi_base + (reg)) | |
40 | ||
41 | ||
42 | /* | |
43 | * Initialize the TWI hardware registers. | |
44 | */ | |
45 | static void __devinit at91_twi_hwinit(void) | |
46 | { | |
47 | unsigned long cdiv, ckdiv; | |
48 | ||
49 | at91_twi_write(AT91_TWI_IDR, 0xffffffff); /* Disable all interrupts */ | |
50 | at91_twi_write(AT91_TWI_CR, AT91_TWI_SWRST); /* Reset peripheral */ | |
51 | at91_twi_write(AT91_TWI_CR, AT91_TWI_MSEN); /* Set Master mode */ | |
52 | ||
53 | /* Calcuate clock dividers */ | |
54 | cdiv = (clk_get_rate(twi_clk) / (2 * TWI_CLOCK)) - 3; | |
55 | cdiv = cdiv + 1; /* round up */ | |
56 | ckdiv = 0; | |
57 | while (cdiv > 255) { | |
58 | ckdiv++; | |
59 | cdiv = cdiv >> 1; | |
60 | } | |
61 | ||
62 | if (cpu_is_at91rm9200()) { /* AT91RM9200 Errata #22 */ | |
63 | if (ckdiv > 5) { | |
64 | printk(KERN_ERR "AT91 I2C: Invalid TWI_CLOCK value!\n"); | |
65 | ckdiv = 5; | |
66 | } | |
67 | } | |
68 | ||
69 | at91_twi_write(AT91_TWI_CWGR, (ckdiv << 16) | (cdiv << 8) | cdiv); | |
70 | } | |
71 | ||
72 | /* | |
73 | * Poll the i2c status register until the specified bit is set. | |
74 | * Returns 0 if timed out (100 msec). | |
75 | */ | |
76 | static short at91_poll_status(unsigned long bit) | |
77 | { | |
78 | int loop_cntr = 10000; | |
79 | ||
80 | do { | |
81 | udelay(10); | |
82 | } while (!(at91_twi_read(AT91_TWI_SR) & bit) && (--loop_cntr > 0)); | |
83 | ||
84 | return (loop_cntr > 0); | |
85 | } | |
86 | ||
87 | static int xfer_read(struct i2c_adapter *adap, unsigned char *buf, int length) | |
88 | { | |
89 | /* Send Start */ | |
90 | at91_twi_write(AT91_TWI_CR, AT91_TWI_START); | |
91 | ||
92 | /* Read data */ | |
93 | while (length--) { | |
94 | if (!length) /* need to send Stop before reading last byte */ | |
95 | at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP); | |
96 | if (!at91_poll_status(AT91_TWI_RXRDY)) { | |
97 | dev_dbg(&adap->dev, "RXRDY timeout\n"); | |
98 | return -ETIMEDOUT; | |
99 | } | |
100 | *buf++ = (at91_twi_read(AT91_TWI_RHR) & 0xff); | |
101 | } | |
102 | ||
103 | return 0; | |
104 | } | |
105 | ||
106 | static int xfer_write(struct i2c_adapter *adap, unsigned char *buf, int length) | |
107 | { | |
108 | /* Load first byte into transmitter */ | |
109 | at91_twi_write(AT91_TWI_THR, *buf++); | |
110 | ||
111 | /* Send Start */ | |
112 | at91_twi_write(AT91_TWI_CR, AT91_TWI_START); | |
113 | ||
114 | do { | |
115 | if (!at91_poll_status(AT91_TWI_TXRDY)) { | |
116 | dev_dbg(&adap->dev, "TXRDY timeout\n"); | |
117 | return -ETIMEDOUT; | |
118 | } | |
119 | ||
120 | length--; /* byte was transmitted */ | |
121 | ||
122 | if (length > 0) /* more data to send? */ | |
123 | at91_twi_write(AT91_TWI_THR, *buf++); | |
124 | } while (length); | |
125 | ||
126 | /* Send Stop */ | |
127 | at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP); | |
128 | ||
129 | return 0; | |
130 | } | |
131 | ||
132 | /* | |
133 | * Generic i2c master transfer entrypoint. | |
134 | * | |
135 | * Note: We do not use Atmel's feature of storing the "internal device address". | |
96acafe0 | 136 | * Instead the "internal device address" has to be written using a separate |
813e30e9 AV |
137 | * i2c message. |
138 | * http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-September/024411.html | |
139 | */ | |
140 | static int at91_xfer(struct i2c_adapter *adap, struct i2c_msg *pmsg, int num) | |
141 | { | |
142 | int i, ret; | |
143 | ||
144 | dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num); | |
145 | ||
146 | for (i = 0; i < num; i++) { | |
147 | dev_dbg(&adap->dev, " #%d: %sing %d byte%s %s 0x%02x\n", i, | |
148 | pmsg->flags & I2C_M_RD ? "read" : "writ", | |
149 | pmsg->len, pmsg->len > 1 ? "s" : "", | |
150 | pmsg->flags & I2C_M_RD ? "from" : "to", pmsg->addr); | |
151 | ||
152 | at91_twi_write(AT91_TWI_MMR, (pmsg->addr << 16) | |
153 | | ((pmsg->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0)); | |
154 | ||
155 | if (pmsg->len && pmsg->buf) { /* sanity check */ | |
156 | if (pmsg->flags & I2C_M_RD) | |
157 | ret = xfer_read(adap, pmsg->buf, pmsg->len); | |
158 | else | |
159 | ret = xfer_write(adap, pmsg->buf, pmsg->len); | |
160 | ||
161 | if (ret) | |
162 | return ret; | |
163 | ||
164 | /* Wait until transfer is finished */ | |
165 | if (!at91_poll_status(AT91_TWI_TXCOMP)) { | |
166 | dev_dbg(&adap->dev, "TXCOMP timeout\n"); | |
167 | return -ETIMEDOUT; | |
168 | } | |
169 | } | |
170 | dev_dbg(&adap->dev, "transfer complete\n"); | |
171 | pmsg++; /* next message */ | |
172 | } | |
173 | return i; | |
174 | } | |
175 | ||
176 | /* | |
177 | * Return list of supported functionality. | |
178 | */ | |
179 | static u32 at91_func(struct i2c_adapter *adapter) | |
180 | { | |
181 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; | |
182 | } | |
183 | ||
184 | static struct i2c_algorithm at91_algorithm = { | |
185 | .master_xfer = at91_xfer, | |
186 | .functionality = at91_func, | |
187 | }; | |
188 | ||
189 | /* | |
190 | * Main initialization routine. | |
191 | */ | |
192 | static int __devinit at91_i2c_probe(struct platform_device *pdev) | |
193 | { | |
194 | struct i2c_adapter *adapter; | |
195 | struct resource *res; | |
196 | int rc; | |
197 | ||
198 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
199 | if (!res) | |
200 | return -ENXIO; | |
201 | ||
c6ffddea | 202 | if (!request_mem_region(res->start, resource_size(res), "at91_i2c")) |
813e30e9 AV |
203 | return -EBUSY; |
204 | ||
c6ffddea | 205 | twi_base = ioremap(res->start, resource_size(res)); |
813e30e9 AV |
206 | if (!twi_base) { |
207 | rc = -ENOMEM; | |
208 | goto fail0; | |
209 | } | |
210 | ||
211 | twi_clk = clk_get(NULL, "twi_clk"); | |
212 | if (IS_ERR(twi_clk)) { | |
213 | dev_err(&pdev->dev, "no clock defined\n"); | |
214 | rc = -ENODEV; | |
215 | goto fail1; | |
216 | } | |
217 | ||
218 | adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL); | |
219 | if (adapter == NULL) { | |
220 | dev_err(&pdev->dev, "can't allocate inteface!\n"); | |
221 | rc = -ENOMEM; | |
222 | goto fail2; | |
223 | } | |
66c7acf6 | 224 | snprintf(adapter->name, sizeof(adapter->name), "AT91"); |
813e30e9 AV |
225 | adapter->algo = &at91_algorithm; |
226 | adapter->class = I2C_CLASS_HWMON; | |
227 | adapter->dev.parent = &pdev->dev; | |
6e99806e | 228 | /* adapter->id == 0 ... only one TWI controller for now */ |
813e30e9 AV |
229 | |
230 | platform_set_drvdata(pdev, adapter); | |
231 | ||
232 | clk_enable(twi_clk); /* enable peripheral clock */ | |
233 | at91_twi_hwinit(); /* initialize TWI controller */ | |
234 | ||
6e99806e | 235 | rc = i2c_add_numbered_adapter(adapter); |
813e30e9 AV |
236 | if (rc) { |
237 | dev_err(&pdev->dev, "Adapter %s registration failed\n", | |
238 | adapter->name); | |
239 | goto fail3; | |
240 | } | |
241 | ||
242 | dev_info(&pdev->dev, "AT91 i2c bus driver.\n"); | |
243 | return 0; | |
244 | ||
245 | fail3: | |
246 | platform_set_drvdata(pdev, NULL); | |
247 | kfree(adapter); | |
248 | clk_disable(twi_clk); | |
249 | fail2: | |
250 | clk_put(twi_clk); | |
251 | fail1: | |
252 | iounmap(twi_base); | |
253 | fail0: | |
c6ffddea | 254 | release_mem_region(res->start, resource_size(res)); |
813e30e9 AV |
255 | |
256 | return rc; | |
257 | } | |
258 | ||
259 | static int __devexit at91_i2c_remove(struct platform_device *pdev) | |
260 | { | |
261 | struct i2c_adapter *adapter = platform_get_drvdata(pdev); | |
262 | struct resource *res; | |
263 | int rc; | |
264 | ||
265 | rc = i2c_del_adapter(adapter); | |
266 | platform_set_drvdata(pdev, NULL); | |
267 | ||
268 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
269 | iounmap(twi_base); | |
c6ffddea | 270 | release_mem_region(res->start, resource_size(res)); |
813e30e9 AV |
271 | |
272 | clk_disable(twi_clk); /* disable peripheral clock */ | |
273 | clk_put(twi_clk); | |
274 | ||
275 | return rc; | |
276 | } | |
277 | ||
278 | #ifdef CONFIG_PM | |
279 | ||
280 | /* NOTE: could save a few mA by keeping clock off outside of at91_xfer... */ | |
281 | ||
282 | static int at91_i2c_suspend(struct platform_device *pdev, pm_message_t mesg) | |
283 | { | |
284 | clk_disable(twi_clk); | |
285 | return 0; | |
286 | } | |
287 | ||
288 | static int at91_i2c_resume(struct platform_device *pdev) | |
289 | { | |
290 | return clk_enable(twi_clk); | |
291 | } | |
292 | ||
293 | #else | |
294 | #define at91_i2c_suspend NULL | |
295 | #define at91_i2c_resume NULL | |
296 | #endif | |
297 | ||
6e99806e | 298 | /* work with "modprobe at91_i2c" from hotplugging or coldplugging */ |
add8eda7 | 299 | MODULE_ALIAS("platform:at91_i2c"); |
6e99806e | 300 | |
813e30e9 AV |
301 | static struct platform_driver at91_i2c_driver = { |
302 | .probe = at91_i2c_probe, | |
303 | .remove = __devexit_p(at91_i2c_remove), | |
304 | .suspend = at91_i2c_suspend, | |
305 | .resume = at91_i2c_resume, | |
306 | .driver = { | |
307 | .name = "at91_i2c", | |
308 | .owner = THIS_MODULE, | |
309 | }, | |
310 | }; | |
311 | ||
312 | static int __init at91_i2c_init(void) | |
313 | { | |
314 | return platform_driver_register(&at91_i2c_driver); | |
315 | } | |
316 | ||
317 | static void __exit at91_i2c_exit(void) | |
318 | { | |
319 | platform_driver_unregister(&at91_i2c_driver); | |
320 | } | |
321 | ||
322 | module_init(at91_i2c_init); | |
323 | module_exit(at91_i2c_exit); | |
324 | ||
325 | MODULE_AUTHOR("Rick Bronson"); | |
326 | MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91"); | |
327 | MODULE_LICENSE("GPL"); |