1 /*
2 * I2C Driver for Atmel ATSHA204 over I2C
3 *
4 * Copyright (C) 2014 Josh Datko, Cryptotronix, jbd@cryptotronix.com
5 * 2016 Tomas Hlavacek, CZ.NIC, tmshlvck@gmail.com
6 * 2017 Marek Behún, CZ.NIC, kabel@kernel.org
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13 #include <common.h>
14 #include <dm.h>
15 #include <i2c.h>
16 #include <errno.h>
17 #include <atsha204a-i2c.h>
18 #include <log.h>
19 #include <asm/global_data.h>
20 #include <linux/delay.h>
21 #include <linux/bitrev.h>
22 #include <u-boot/crc.h>
23
24 #define ATSHA204A_TWLO_US 60
25 #define ATSHA204A_TWHI_US 2500
26 #define ATSHA204A_TRANSACTION_TIMEOUT 100000
27 #define ATSHA204A_TRANSACTION_RETRY 5
28 #define ATSHA204A_EXECTIME 5000
29
30 DECLARE_GLOBAL_DATA_PTR;
31
atsha204a_crc16(const u8 * buffer,size_t len)32 static inline u16 atsha204a_crc16(const u8 *buffer, size_t len)
33 {
34 return bitrev16(crc16(0, buffer, len));
35 }
36
atsha204a_send(struct udevice * dev,const u8 * buf,u8 len)37 static int atsha204a_send(struct udevice *dev, const u8 *buf, u8 len)
38 {
39 fdt_addr_t *priv = dev_get_priv(dev);
40 struct i2c_msg msg;
41
42 msg.addr = *priv;
43 msg.flags = I2C_M_STOP;
44 msg.len = len;
45 msg.buf = (u8 *) buf;
46
47 return dm_i2c_xfer(dev, &msg, 1);
48 }
49
atsha204a_recv(struct udevice * dev,u8 * buf,u8 len)50 static int atsha204a_recv(struct udevice *dev, u8 *buf, u8 len)
51 {
52 fdt_addr_t *priv = dev_get_priv(dev);
53 struct i2c_msg msg;
54
55 msg.addr = *priv;
56 msg.flags = I2C_M_RD | I2C_M_STOP;
57 msg.len = len;
58 msg.buf = (u8 *) buf;
59
60 return dm_i2c_xfer(dev, &msg, 1);
61 }
62
atsha204a_recv_resp(struct udevice * dev,struct atsha204a_resp * resp)63 static int atsha204a_recv_resp(struct udevice *dev,
64 struct atsha204a_resp *resp)
65 {
66 int res;
67 u16 resp_crc, computed_crc;
68 u8 *p = (u8 *) resp;
69
70 res = atsha204a_recv(dev, p, 4);
71 if (res)
72 return res;
73
74 if (resp->length > 4) {
75 if (resp->length > sizeof(*resp))
76 return -EMSGSIZE;
77
78 res = atsha204a_recv(dev, p + 4, resp->length - 4);
79 if (res)
80 return res;
81 }
82
83 resp_crc = (u16) p[resp->length - 2]
84 | (((u16) p[resp->length - 1]) << 8);
85 computed_crc = atsha204a_crc16(p, resp->length - 2);
86
87 if (resp_crc != computed_crc) {
88 debug("Invalid checksum in ATSHA204A response\n");
89 return -EBADMSG;
90 }
91
92 return 0;
93 }
94
atsha204a_wakeup(struct udevice * dev)95 int atsha204a_wakeup(struct udevice *dev)
96 {
97 u8 req[4];
98 struct atsha204a_resp resp;
99 int try, res;
100
101 debug("Waking up ATSHA204A\n");
102
103 for (try = 1; try <= 10; ++try) {
104 debug("Try %i... ", try);
105
106 /*
107 * The device ignores any levels or transitions on the SCL pin
108 * when the device is idle, asleep or during waking up.
109 * Don't check for error when waking up the device.
110 */
111 memset(req, 0, 4);
112 atsha204a_send(dev, req, 4);
113
114 udelay(ATSHA204A_TWLO_US + ATSHA204A_TWHI_US);
115
116 res = atsha204a_recv_resp(dev, &resp);
117 if (res) {
118 debug("failed on receiving response, ending\n");
119 return res;
120 }
121
122 if (resp.code != ATSHA204A_STATUS_AFTER_WAKE) {
123 debug ("failed (responce code = %02x), ending\n",
124 resp.code);
125 return -EBADMSG;
126 }
127
128 debug("success\n");
129 return 0;
130 }
131
132 return -ETIMEDOUT;
133 }
134
atsha204a_idle(struct udevice * dev)135 int atsha204a_idle(struct udevice *dev)
136 {
137 int res;
138 u8 req = ATSHA204A_FUNC_IDLE;
139
140 res = atsha204a_send(dev, &req, 1);
141 if (res)
142 debug("Failed putting ATSHA204A idle\n");
143 return res;
144 }
145
atsha204a_sleep(struct udevice * dev)146 int atsha204a_sleep(struct udevice *dev)
147 {
148 int res;
149 u8 req = ATSHA204A_FUNC_IDLE;
150
151 res = atsha204a_send(dev, &req, 1);
152 if (res)
153 debug("Failed putting ATSHA204A to sleep\n");
154 return res;
155 }
156
atsha204a_transaction(struct udevice * dev,struct atsha204a_req * req,struct atsha204a_resp * resp)157 static int atsha204a_transaction(struct udevice *dev, struct atsha204a_req *req,
158 struct atsha204a_resp *resp)
159 {
160 int res, timeout = ATSHA204A_TRANSACTION_TIMEOUT;
161
162 res = atsha204a_send(dev, (u8 *) req, req->length + 1);
163 if (res) {
164 debug("ATSHA204A transaction send failed\n");
165 return -EBUSY;
166 }
167
168 do {
169 udelay(ATSHA204A_EXECTIME);
170 res = atsha204a_recv_resp(dev, resp);
171 if (!res || res == -EMSGSIZE || res == -EBADMSG)
172 break;
173
174 debug("ATSHA204A transaction polling for response "
175 "(timeout = %d)\n", timeout);
176
177 timeout -= ATSHA204A_EXECTIME;
178 } while (timeout > 0);
179
180 if (timeout <= 0) {
181 debug("ATSHA204A transaction timed out\n");
182 return -ETIMEDOUT;
183 }
184
185 return res;
186 }
187
atsha204a_req_crc32(struct atsha204a_req * req)188 static void atsha204a_req_crc32(struct atsha204a_req *req)
189 {
190 u8 *p = (u8 *) req;
191 u16 computed_crc;
192 u16 *crc_ptr = (u16 *) &p[req->length - 1];
193
194 /* The buffer to crc16 starts at byte 1, not 0 */
195 computed_crc = atsha204a_crc16(p + 1, req->length - 2);
196
197 *crc_ptr = cpu_to_le16(computed_crc);
198 }
199
atsha204a_read(struct udevice * dev,enum atsha204a_zone zone,bool read32,u16 addr,u8 * buffer)200 int atsha204a_read(struct udevice *dev, enum atsha204a_zone zone, bool read32,
201 u16 addr, u8 *buffer)
202 {
203 int res, retry = ATSHA204A_TRANSACTION_RETRY;
204 struct atsha204a_req req;
205 struct atsha204a_resp resp;
206
207 req.function = ATSHA204A_FUNC_COMMAND;
208 req.length = 7;
209 req.command = ATSHA204A_CMD_READ;
210
211 req.param1 = (u8) zone;
212 if (read32)
213 req.param1 |= 0x80;
214
215 req.param2 = cpu_to_le16(addr);
216
217 atsha204a_req_crc32(&req);
218
219 do {
220 res = atsha204a_transaction(dev, &req, &resp);
221 if (!res)
222 break;
223
224 debug("ATSHA204A read retry (%d)\n", retry);
225 retry--;
226 atsha204a_wakeup(dev);
227 } while (retry >= 0);
228
229 if (res) {
230 debug("ATSHA204A read failed\n");
231 return res;
232 }
233
234 if (resp.length != (read32 ? 32 : 4) + 3) {
235 debug("ATSHA204A read bad response length (%d)\n",
236 resp.length);
237 return -EBADMSG;
238 }
239
240 memcpy(buffer, ((u8 *) &resp) + 1, read32 ? 32 : 4);
241
242 return 0;
243 }
244
atsha204a_get_random(struct udevice * dev,u8 * buffer,size_t max)245 int atsha204a_get_random(struct udevice *dev, u8 *buffer, size_t max)
246 {
247 int res;
248 struct atsha204a_req req;
249 struct atsha204a_resp resp;
250
251 req.function = ATSHA204A_FUNC_COMMAND;
252 req.length = 7;
253 req.command = ATSHA204A_CMD_RANDOM;
254
255 req.param1 = 1;
256 req.param2 = 0;
257
258 /* We do not have to compute the checksum dynamically */
259 req.data[0] = 0x27;
260 req.data[1] = 0x47;
261
262 res = atsha204a_transaction(dev, &req, &resp);
263 if (res) {
264 debug("ATSHA204A random transaction failed\n");
265 return res;
266 }
267
268 memcpy(buffer, ((u8 *) &resp) + 1, max >= 32 ? 32 : max);
269 return 0;
270 }
271
atsha204a_of_to_plat(struct udevice * dev)272 static int atsha204a_of_to_plat(struct udevice *dev)
273 {
274 fdt_addr_t *priv = dev_get_priv(dev);
275 fdt_addr_t addr;
276
277 addr = dev_read_addr(dev);
278 if (addr == FDT_ADDR_T_NONE) {
279 debug("Can't get ATSHA204A I2C base address\n");
280 return -ENXIO;
281 }
282
283 *priv = addr;
284 return 0;
285 }
286
287 static const struct udevice_id atsha204a_ids[] = {
288 { .compatible = "atmel,atsha204" },
289 { .compatible = "atmel,atsha204a" },
290 { }
291 };
292
293 U_BOOT_DRIVER(atsha204) = {
294 .name = "atsha204",
295 .id = UCLASS_MISC,
296 .of_match = atsha204a_ids,
297 .of_to_plat = atsha204a_of_to_plat,
298 .priv_auto = sizeof(fdt_addr_t),
299 };
300