1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * i2c-au1550.c: SMBus (i2c) adapter for Alchemy PSC interface
4 * Copyright (C) 2004 Embedded Edge, LLC <dan@embeddededge.com>
5 *
6 * 2.6 port by Matt Porter <mporter@kernel.crashing.org>
7 *
8 * The documentation describes this as an SMBus controller, but it doesn't
9 * understand any of the SMBus protocol in hardware. It's really an I2C
10 * controller that could emulate most of the SMBus in software.
11 *
12 * This is just a skeleton adapter to use with the Au1550 PSC
13 * algorithm. It was developed for the Pb1550, but will work with
14 * any Au1550 board that has a similar PSC configuration.
15 */
16
17 #include <linux/delay.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/platform_device.h>
21 #include <linux/errno.h>
22 #include <linux/i2c.h>
23 #include <linux/slab.h>
24
25 #include <asm/mach-au1x00/au1000.h>
26 #include <asm/mach-au1x00/au1xxx_psc.h>
27
28 #define PSC_SEL 0x00
29 #define PSC_CTRL 0x04
30 #define PSC_SMBCFG 0x08
31 #define PSC_SMBMSK 0x0C
32 #define PSC_SMBPCR 0x10
33 #define PSC_SMBSTAT 0x14
34 #define PSC_SMBEVNT 0x18
35 #define PSC_SMBTXRX 0x1C
36 #define PSC_SMBTMR 0x20
37
38 struct i2c_au1550_data {
39 void __iomem *psc_base;
40 int xfer_timeout;
41 struct i2c_adapter adap;
42 };
43
WR(struct i2c_au1550_data * a,int r,unsigned long v)44 static inline void WR(struct i2c_au1550_data *a, int r, unsigned long v)
45 {
46 __raw_writel(v, a->psc_base + r);
47 wmb();
48 }
49
RD(struct i2c_au1550_data * a,int r)50 static inline unsigned long RD(struct i2c_au1550_data *a, int r)
51 {
52 return __raw_readl(a->psc_base + r);
53 }
54
wait_xfer_done(struct i2c_au1550_data * adap)55 static int wait_xfer_done(struct i2c_au1550_data *adap)
56 {
57 int i;
58
59 /* Wait for Tx Buffer Empty */
60 for (i = 0; i < adap->xfer_timeout; i++) {
61 if (RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_TE)
62 return 0;
63
64 udelay(1);
65 }
66
67 return -ETIMEDOUT;
68 }
69
wait_ack(struct i2c_au1550_data * adap)70 static int wait_ack(struct i2c_au1550_data *adap)
71 {
72 unsigned long stat;
73
74 if (wait_xfer_done(adap))
75 return -ETIMEDOUT;
76
77 stat = RD(adap, PSC_SMBEVNT);
78 if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0)
79 return -ETIMEDOUT;
80
81 return 0;
82 }
83
wait_master_done(struct i2c_au1550_data * adap)84 static int wait_master_done(struct i2c_au1550_data *adap)
85 {
86 int i;
87
88 /* Wait for Master Done. */
89 for (i = 0; i < 2 * adap->xfer_timeout; i++) {
90 if ((RD(adap, PSC_SMBEVNT) & PSC_SMBEVNT_MD) != 0)
91 return 0;
92 udelay(1);
93 }
94
95 return -ETIMEDOUT;
96 }
97
98 static int
do_address(struct i2c_au1550_data * adap,unsigned int addr,int rd,int q)99 do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
100 {
101 unsigned long stat;
102
103 /* Reset the FIFOs, clear events. */
104 stat = RD(adap, PSC_SMBSTAT);
105 WR(adap, PSC_SMBEVNT, PSC_SMBEVNT_ALLCLR);
106
107 if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) {
108 WR(adap, PSC_SMBPCR, PSC_SMBPCR_DC);
109 while ((RD(adap, PSC_SMBPCR) & PSC_SMBPCR_DC) != 0)
110 cpu_relax();
111 udelay(50);
112 }
113
114 /* Write out the i2c chip address and specify operation */
115 addr <<= 1;
116 if (rd)
117 addr |= 1;
118
119 /* zero-byte xfers stop immediately */
120 if (q)
121 addr |= PSC_SMBTXRX_STP;
122
123 /* Put byte into fifo, start up master. */
124 WR(adap, PSC_SMBTXRX, addr);
125 WR(adap, PSC_SMBPCR, PSC_SMBPCR_MS);
126 if (wait_ack(adap))
127 return -EIO;
128 return (q) ? wait_master_done(adap) : 0;
129 }
130
wait_for_rx_byte(struct i2c_au1550_data * adap,unsigned char * out)131 static int wait_for_rx_byte(struct i2c_au1550_data *adap, unsigned char *out)
132 {
133 int j;
134
135 if (wait_xfer_done(adap))
136 return -EIO;
137
138 j = adap->xfer_timeout * 100;
139 do {
140 j--;
141 if (j <= 0)
142 return -EIO;
143
144 if ((RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_RE) == 0)
145 j = 0;
146 else
147 udelay(1);
148 } while (j > 0);
149
150 *out = RD(adap, PSC_SMBTXRX);
151
152 return 0;
153 }
154
i2c_read(struct i2c_au1550_data * adap,unsigned char * buf,unsigned int len)155 static int i2c_read(struct i2c_au1550_data *adap, unsigned char *buf,
156 unsigned int len)
157 {
158 int i;
159
160 if (len == 0)
161 return 0;
162
163 /* A read is performed by stuffing the transmit fifo with
164 * zero bytes for timing, waiting for bytes to appear in the
165 * receive fifo, then reading the bytes.
166 */
167 i = 0;
168 while (i < (len - 1)) {
169 WR(adap, PSC_SMBTXRX, 0);
170 if (wait_for_rx_byte(adap, &buf[i]))
171 return -EIO;
172
173 i++;
174 }
175
176 /* The last byte has to indicate transfer done. */
177 WR(adap, PSC_SMBTXRX, PSC_SMBTXRX_STP);
178 if (wait_master_done(adap))
179 return -EIO;
180
181 buf[i] = (unsigned char)(RD(adap, PSC_SMBTXRX) & 0xff);
182 return 0;
183 }
184
i2c_write(struct i2c_au1550_data * adap,unsigned char * buf,unsigned int len)185 static int i2c_write(struct i2c_au1550_data *adap, unsigned char *buf,
186 unsigned int len)
187 {
188 int i;
189 unsigned long data;
190
191 if (len == 0)
192 return 0;
193
194 i = 0;
195 while (i < (len-1)) {
196 data = buf[i];
197 WR(adap, PSC_SMBTXRX, data);
198 if (wait_ack(adap))
199 return -EIO;
200 i++;
201 }
202
203 /* The last byte has to indicate transfer done. */
204 data = buf[i];
205 data |= PSC_SMBTXRX_STP;
206 WR(adap, PSC_SMBTXRX, data);
207 if (wait_master_done(adap))
208 return -EIO;
209 return 0;
210 }
211
212 static int
au1550_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg * msgs,int num)213 au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
214 {
215 struct i2c_au1550_data *adap = i2c_adap->algo_data;
216 struct i2c_msg *p;
217 int i, err = 0;
218
219 WR(adap, PSC_CTRL, PSC_CTRL_ENABLE);
220
221 for (i = 0; !err && i < num; i++) {
222 p = &msgs[i];
223 err = do_address(adap, p->addr, p->flags & I2C_M_RD,
224 (p->len == 0));
225 if (err || !p->len)
226 continue;
227 if (p->flags & I2C_M_RD)
228 err = i2c_read(adap, p->buf, p->len);
229 else
230 err = i2c_write(adap, p->buf, p->len);
231 }
232
233 /* Return the number of messages processed, or the error code.
234 */
235 if (err == 0)
236 err = num;
237
238 WR(adap, PSC_CTRL, PSC_CTRL_SUSPEND);
239
240 return err;
241 }
242
au1550_func(struct i2c_adapter * adap)243 static u32 au1550_func(struct i2c_adapter *adap)
244 {
245 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
246 }
247
248 static const struct i2c_algorithm au1550_algo = {
249 .master_xfer = au1550_xfer,
250 .functionality = au1550_func,
251 };
252
i2c_au1550_setup(struct i2c_au1550_data * priv)253 static void i2c_au1550_setup(struct i2c_au1550_data *priv)
254 {
255 unsigned long cfg;
256
257 WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
258 WR(priv, PSC_SEL, PSC_SEL_PS_SMBUSMODE);
259 WR(priv, PSC_SMBCFG, 0);
260 WR(priv, PSC_CTRL, PSC_CTRL_ENABLE);
261 while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
262 cpu_relax();
263
264 cfg = PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 | PSC_SMBCFG_DD_DISABLE;
265 WR(priv, PSC_SMBCFG, cfg);
266
267 /* Divide by 8 to get a 6.25 MHz clock. The later protocol
268 * timings are based on this clock.
269 */
270 cfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8);
271 WR(priv, PSC_SMBCFG, cfg);
272 WR(priv, PSC_SMBMSK, PSC_SMBMSK_ALLMASK);
273
274 /* Set the protocol timer values. See Table 71 in the
275 * Au1550 Data Book for standard timing values.
276 */
277 WR(priv, PSC_SMBTMR, PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(20) | \
278 PSC_SMBTMR_SET_PU(20) | PSC_SMBTMR_SET_SH(20) | \
279 PSC_SMBTMR_SET_SU(20) | PSC_SMBTMR_SET_CL(20) | \
280 PSC_SMBTMR_SET_CH(20));
281
282 cfg |= PSC_SMBCFG_DE_ENABLE;
283 WR(priv, PSC_SMBCFG, cfg);
284 while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0)
285 cpu_relax();
286
287 WR(priv, PSC_CTRL, PSC_CTRL_SUSPEND);
288 }
289
i2c_au1550_disable(struct i2c_au1550_data * priv)290 static void i2c_au1550_disable(struct i2c_au1550_data *priv)
291 {
292 WR(priv, PSC_SMBCFG, 0);
293 WR(priv, PSC_CTRL, PSC_CTRL_DISABLE);
294 }
295
296 /*
297 * registering functions to load algorithms at runtime
298 * Prior to calling us, the 50MHz clock frequency and routing
299 * must have been set up for the PSC indicated by the adapter.
300 */
301 static int
i2c_au1550_probe(struct platform_device * pdev)302 i2c_au1550_probe(struct platform_device *pdev)
303 {
304 struct i2c_au1550_data *priv;
305 int ret;
306
307 priv = devm_kzalloc(&pdev->dev, sizeof(struct i2c_au1550_data),
308 GFP_KERNEL);
309 if (!priv)
310 return -ENOMEM;
311
312 priv->psc_base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
313 if (IS_ERR(priv->psc_base))
314 return PTR_ERR(priv->psc_base);
315
316 priv->xfer_timeout = 200;
317
318 priv->adap.nr = pdev->id;
319 priv->adap.algo = &au1550_algo;
320 priv->adap.algo_data = priv;
321 priv->adap.dev.parent = &pdev->dev;
322 strscpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name));
323
324 /* Now, set up the PSC for SMBus PIO mode. */
325 i2c_au1550_setup(priv);
326
327 ret = i2c_add_numbered_adapter(&priv->adap);
328 if (ret) {
329 i2c_au1550_disable(priv);
330 return ret;
331 }
332
333 platform_set_drvdata(pdev, priv);
334 return 0;
335 }
336
i2c_au1550_remove(struct platform_device * pdev)337 static void i2c_au1550_remove(struct platform_device *pdev)
338 {
339 struct i2c_au1550_data *priv = platform_get_drvdata(pdev);
340
341 i2c_del_adapter(&priv->adap);
342 i2c_au1550_disable(priv);
343 }
344
i2c_au1550_suspend(struct device * dev)345 static int i2c_au1550_suspend(struct device *dev)
346 {
347 struct i2c_au1550_data *priv = dev_get_drvdata(dev);
348
349 i2c_au1550_disable(priv);
350
351 return 0;
352 }
353
i2c_au1550_resume(struct device * dev)354 static int i2c_au1550_resume(struct device *dev)
355 {
356 struct i2c_au1550_data *priv = dev_get_drvdata(dev);
357
358 i2c_au1550_setup(priv);
359
360 return 0;
361 }
362
363 static DEFINE_SIMPLE_DEV_PM_OPS(i2c_au1550_pmops,
364 i2c_au1550_suspend, i2c_au1550_resume);
365
366 static struct platform_driver au1xpsc_smbus_driver = {
367 .driver = {
368 .name = "au1xpsc_smbus",
369 .pm = pm_sleep_ptr(&i2c_au1550_pmops),
370 },
371 .probe = i2c_au1550_probe,
372 .remove_new = i2c_au1550_remove,
373 };
374
375 module_platform_driver(au1xpsc_smbus_driver);
376
377 MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC.");
378 MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550");
379 MODULE_LICENSE("GPL");
380 MODULE_ALIAS("platform:au1xpsc_smbus");
381