1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 i2c-isch.c - Linux kernel driver for Intel SCH chipset SMBus
4 - Based on i2c-piix4.c
5 Copyright (c) 1998 - 2002 Frodo Looijaard <frodol@dds.nl> and
6 Philip Edelbrock <phil@netroedge.com>
7 - Intel SCH support
8 Copyright (c) 2007 - 2008 Jacob Jun Pan <jacob.jun.pan@intel.com>
9
10 */
11
12 /*
13 Supports:
14 Intel SCH chipsets (AF82US15W, AF82US15L, AF82UL11L)
15 Note: we assume there can only be one device, with one SMBus interface.
16 */
17
18 #include <linux/module.h>
19 #include <linux/platform_device.h>
20 #include <linux/kernel.h>
21 #include <linux/delay.h>
22 #include <linux/stddef.h>
23 #include <linux/ioport.h>
24 #include <linux/i2c.h>
25 #include <linux/io.h>
26
27 /* SCH SMBus address offsets */
28 #define SMBHSTCNT (0 + sch_smba)
29 #define SMBHSTSTS (1 + sch_smba)
30 #define SMBHSTCLK (2 + sch_smba)
31 #define SMBHSTADD (4 + sch_smba) /* TSA */
32 #define SMBHSTCMD (5 + sch_smba)
33 #define SMBHSTDAT0 (6 + sch_smba)
34 #define SMBHSTDAT1 (7 + sch_smba)
35 #define SMBBLKDAT (0x20 + sch_smba)
36
37 /* Other settings */
38 #define MAX_RETRIES 5000
39
40 /* I2C constants */
41 #define SCH_QUICK 0x00
42 #define SCH_BYTE 0x01
43 #define SCH_BYTE_DATA 0x02
44 #define SCH_WORD_DATA 0x03
45 #define SCH_BLOCK_DATA 0x05
46
47 static unsigned short sch_smba;
48 static struct i2c_adapter sch_adapter;
49 static int backbone_speed = 33000; /* backbone speed in kHz */
50 module_param(backbone_speed, int, S_IRUSR | S_IWUSR);
51 MODULE_PARM_DESC(backbone_speed, "Backbone speed in kHz, (default = 33000)");
52
53 /*
54 * Start the i2c transaction -- the i2c_access will prepare the transaction
55 * and this function will execute it.
56 * return 0 for success and others for failure.
57 */
sch_transaction(void)58 static int sch_transaction(void)
59 {
60 int temp;
61 int result = 0;
62 int retries = 0;
63
64 dev_dbg(&sch_adapter.dev, "Transaction (pre): CNT=%02x, CMD=%02x, "
65 "ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb(SMBHSTCNT),
66 inb(SMBHSTCMD), inb(SMBHSTADD), inb(SMBHSTDAT0),
67 inb(SMBHSTDAT1));
68
69 /* Make sure the SMBus host is ready to start transmitting */
70 temp = inb(SMBHSTSTS) & 0x0f;
71 if (temp) {
72 /* Can not be busy since we checked it in sch_access */
73 if (temp & 0x01) {
74 dev_dbg(&sch_adapter.dev, "Completion (%02x). "
75 "Clear...\n", temp);
76 }
77 if (temp & 0x06) {
78 dev_dbg(&sch_adapter.dev, "SMBus error (%02x). "
79 "Resetting...\n", temp);
80 }
81 outb(temp, SMBHSTSTS);
82 temp = inb(SMBHSTSTS) & 0x0f;
83 if (temp) {
84 dev_err(&sch_adapter.dev,
85 "SMBus is not ready: (%02x)\n", temp);
86 return -EAGAIN;
87 }
88 }
89
90 /* start the transaction by setting bit 4 */
91 outb(inb(SMBHSTCNT) | 0x10, SMBHSTCNT);
92
93 do {
94 usleep_range(100, 200);
95 temp = inb(SMBHSTSTS) & 0x0f;
96 } while ((temp & 0x08) && (retries++ < MAX_RETRIES));
97
98 /* If the SMBus is still busy, we give up */
99 if (retries > MAX_RETRIES) {
100 dev_err(&sch_adapter.dev, "SMBus Timeout!\n");
101 result = -ETIMEDOUT;
102 } else if (temp & 0x04) {
103 result = -EIO;
104 dev_dbg(&sch_adapter.dev, "Bus collision! SMBus may be "
105 "locked until next hard reset. (sorry!)\n");
106 /* Clock stops and slave is stuck in mid-transmission */
107 } else if (temp & 0x02) {
108 result = -EIO;
109 dev_err(&sch_adapter.dev, "Error: no response!\n");
110 } else if (temp & 0x01) {
111 dev_dbg(&sch_adapter.dev, "Post complete!\n");
112 outb(temp, SMBHSTSTS);
113 temp = inb(SMBHSTSTS) & 0x07;
114 if (temp & 0x06) {
115 /* Completion clear failed */
116 dev_dbg(&sch_adapter.dev, "Failed reset at end of "
117 "transaction (%02x), Bus error!\n", temp);
118 }
119 } else {
120 result = -ENXIO;
121 dev_dbg(&sch_adapter.dev, "No such address.\n");
122 }
123 dev_dbg(&sch_adapter.dev, "Transaction (post): CNT=%02x, CMD=%02x, "
124 "ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb(SMBHSTCNT),
125 inb(SMBHSTCMD), inb(SMBHSTADD), inb(SMBHSTDAT0),
126 inb(SMBHSTDAT1));
127 return result;
128 }
129
130 /*
131 * This is the main access entry for i2c-sch access
132 * adap is i2c_adapter pointer, addr is the i2c device bus address, read_write
133 * (0 for read and 1 for write), size is i2c transaction type and data is the
134 * union of transaction for data to be transferred or data read from bus.
135 * return 0 for success and others for failure.
136 */
sch_access(struct i2c_adapter * adap,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data)137 static s32 sch_access(struct i2c_adapter *adap, u16 addr,
138 unsigned short flags, char read_write,
139 u8 command, int size, union i2c_smbus_data *data)
140 {
141 int i, len, temp, rc;
142
143 /* Make sure the SMBus host is not busy */
144 temp = inb(SMBHSTSTS) & 0x0f;
145 if (temp & 0x08) {
146 dev_dbg(&sch_adapter.dev, "SMBus busy (%02x)\n", temp);
147 return -EAGAIN;
148 }
149 temp = inw(SMBHSTCLK);
150 if (!temp) {
151 /*
152 * We can't determine if we have 33 or 25 MHz clock for
153 * SMBus, so expect 33 MHz and calculate a bus clock of
154 * 100 kHz. If we actually run at 25 MHz the bus will be
155 * run ~75 kHz instead which should do no harm.
156 */
157 dev_notice(&sch_adapter.dev,
158 "Clock divider uninitialized. Setting defaults\n");
159 outw(backbone_speed / (4 * 100), SMBHSTCLK);
160 }
161
162 dev_dbg(&sch_adapter.dev, "access size: %d %s\n", size,
163 (read_write)?"READ":"WRITE");
164 switch (size) {
165 case I2C_SMBUS_QUICK:
166 outb((addr << 1) | read_write, SMBHSTADD);
167 size = SCH_QUICK;
168 break;
169 case I2C_SMBUS_BYTE:
170 outb((addr << 1) | read_write, SMBHSTADD);
171 if (read_write == I2C_SMBUS_WRITE)
172 outb(command, SMBHSTCMD);
173 size = SCH_BYTE;
174 break;
175 case I2C_SMBUS_BYTE_DATA:
176 outb((addr << 1) | read_write, SMBHSTADD);
177 outb(command, SMBHSTCMD);
178 if (read_write == I2C_SMBUS_WRITE)
179 outb(data->byte, SMBHSTDAT0);
180 size = SCH_BYTE_DATA;
181 break;
182 case I2C_SMBUS_WORD_DATA:
183 outb((addr << 1) | read_write, SMBHSTADD);
184 outb(command, SMBHSTCMD);
185 if (read_write == I2C_SMBUS_WRITE) {
186 outb(data->word & 0xff, SMBHSTDAT0);
187 outb((data->word & 0xff00) >> 8, SMBHSTDAT1);
188 }
189 size = SCH_WORD_DATA;
190 break;
191 case I2C_SMBUS_BLOCK_DATA:
192 outb((addr << 1) | read_write, SMBHSTADD);
193 outb(command, SMBHSTCMD);
194 if (read_write == I2C_SMBUS_WRITE) {
195 len = data->block[0];
196 if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
197 return -EINVAL;
198 outb(len, SMBHSTDAT0);
199 for (i = 1; i <= len; i++)
200 outb(data->block[i], SMBBLKDAT+i-1);
201 }
202 size = SCH_BLOCK_DATA;
203 break;
204 default:
205 dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
206 return -EOPNOTSUPP;
207 }
208 dev_dbg(&sch_adapter.dev, "write size %d to 0x%04x\n", size, SMBHSTCNT);
209 outb((inb(SMBHSTCNT) & 0xb0) | (size & 0x7), SMBHSTCNT);
210
211 rc = sch_transaction();
212 if (rc) /* Error in transaction */
213 return rc;
214
215 if ((read_write == I2C_SMBUS_WRITE) || (size == SCH_QUICK))
216 return 0;
217
218 switch (size) {
219 case SCH_BYTE:
220 case SCH_BYTE_DATA:
221 data->byte = inb(SMBHSTDAT0);
222 break;
223 case SCH_WORD_DATA:
224 data->word = inb(SMBHSTDAT0) + (inb(SMBHSTDAT1) << 8);
225 break;
226 case SCH_BLOCK_DATA:
227 data->block[0] = inb(SMBHSTDAT0);
228 if (data->block[0] == 0 || data->block[0] > I2C_SMBUS_BLOCK_MAX)
229 return -EPROTO;
230 for (i = 1; i <= data->block[0]; i++)
231 data->block[i] = inb(SMBBLKDAT+i-1);
232 break;
233 }
234 return 0;
235 }
236
sch_func(struct i2c_adapter * adapter)237 static u32 sch_func(struct i2c_adapter *adapter)
238 {
239 return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
240 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
241 I2C_FUNC_SMBUS_BLOCK_DATA;
242 }
243
244 static const struct i2c_algorithm smbus_algorithm = {
245 .smbus_xfer = sch_access,
246 .functionality = sch_func,
247 };
248
249 static struct i2c_adapter sch_adapter = {
250 .owner = THIS_MODULE,
251 .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
252 .algo = &smbus_algorithm,
253 };
254
smbus_sch_probe(struct platform_device * dev)255 static int smbus_sch_probe(struct platform_device *dev)
256 {
257 struct resource *res;
258 int retval;
259
260 res = platform_get_resource(dev, IORESOURCE_IO, 0);
261 if (!res)
262 return -EBUSY;
263
264 if (!devm_request_region(&dev->dev, res->start, resource_size(res),
265 dev->name)) {
266 dev_err(&dev->dev, "SMBus region 0x%x already in use!\n",
267 sch_smba);
268 return -EBUSY;
269 }
270
271 sch_smba = res->start;
272
273 dev_dbg(&dev->dev, "SMBA = 0x%X\n", sch_smba);
274
275 /* set up the sysfs linkage to our parent device */
276 sch_adapter.dev.parent = &dev->dev;
277
278 snprintf(sch_adapter.name, sizeof(sch_adapter.name),
279 "SMBus SCH adapter at %04x", sch_smba);
280
281 retval = i2c_add_adapter(&sch_adapter);
282 if (retval)
283 sch_smba = 0;
284
285 return retval;
286 }
287
smbus_sch_remove(struct platform_device * pdev)288 static void smbus_sch_remove(struct platform_device *pdev)
289 {
290 if (sch_smba) {
291 i2c_del_adapter(&sch_adapter);
292 sch_smba = 0;
293 }
294 }
295
296 static struct platform_driver smbus_sch_driver = {
297 .driver = {
298 .name = "isch_smbus",
299 },
300 .probe = smbus_sch_probe,
301 .remove_new = smbus_sch_remove,
302 };
303
304 module_platform_driver(smbus_sch_driver);
305
306 MODULE_AUTHOR("Jacob Pan <jacob.jun.pan@intel.com>");
307 MODULE_DESCRIPTION("Intel SCH SMBus driver");
308 MODULE_LICENSE("GPL");
309 MODULE_ALIAS("platform:isch_smbus");
310