chrome_ec.c revision 266341 
1/*-
2 * Copyright (c) 2014 Ruslan Bukin <br@bsdpad.com>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPREC OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNEC FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINEC INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27/*
28 * Samsung Chromebook Embedded Controller
29 */
30
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD: stable/10/sys/arm/samsung/exynos/chrome_ec.c 266341 2014-05-17 19:37:04Z ian $");
33
34#include <sys/param.h>
35#include <sys/systm.h>
36#include <sys/bus.h>
37#include <sys/kernel.h>
38#include <sys/module.h>
39#include <sys/malloc.h>
40#include <sys/rman.h>
41#include <sys/timeet.h>
42#include <sys/timetc.h>
43#include <sys/watchdog.h>
44#include <sys/gpio.h>
45
46#include <dev/fdt/fdt_common.h>
47#include <dev/ofw/openfirm.h>
48#include <dev/ofw/ofw_bus.h>
49#include <dev/ofw/ofw_bus_subr.h>
50
51#include <machine/bus.h>
52#include <machine/fdt.h>
53#include <machine/cpu.h>
54#include <machine/intr.h>
55
56#include <dev/iicbus/iiconf.h>
57
58#include "iicbus_if.h"
59#include "gpio_if.h"
60
61#include <arm/samsung/exynos/chrome_ec.h>
62
63/* TODO: export to DTS */
64#define OUR_GPIO	177
65#define EC_GPIO		168
66
67struct ec_softc {
68	device_t	dev;
69};
70
71struct ec_softc *ec_sc;
72
73/*
74 * bus_claim, bus_release
75 * both functions used for bus arbitration
76 * in multi-master mode
77 */
78
79static int
80bus_claim(struct ec_softc *sc)
81{
82	device_t gpio_dev;
83	int status;
84
85	gpio_dev = devclass_get_device(devclass_find("gpio"), 0);
86        if (gpio_dev == NULL) {
87		device_printf(sc->dev, "cant find gpio_dev\n");
88		return (1);
89	}
90
91	/* Say we want the bus */
92	GPIO_PIN_SET(gpio_dev, OUR_GPIO, GPIO_PIN_LOW);
93
94	/* Check EC decision */
95	GPIO_PIN_GET(gpio_dev, EC_GPIO, &status);
96
97	if (status == 1) {
98		/* Okay. We have bus */
99		return (0);
100	}
101
102	/* EC is master */
103	return (-1);
104}
105
106static int
107bus_release(struct ec_softc *sc)
108{
109	device_t gpio_dev;
110
111	gpio_dev = devclass_get_device(devclass_find("gpio"), 0);
112        if (gpio_dev == NULL) {
113		device_printf(sc->dev, "cant find gpio_dev\n");
114		return (1);
115	}
116
117	GPIO_PIN_SET(gpio_dev, OUR_GPIO, GPIO_PIN_HIGH);
118
119	return (0);
120}
121
122static int
123ec_probe(device_t dev)
124{
125
126	device_set_desc(dev, "Chromebook Embedded Controller");
127	return (BUS_PROBE_DEFAULT);
128}
129
130static int
131fill_checksum(uint8_t *data_out, int len)
132{
133	int res;
134	int i;
135
136	res = 0;
137	for (i = 0; i < len; i++) {
138		res += data_out[i];
139	}
140
141	data_out[len] = (res & 0xff);
142
143	return (0);
144}
145
146int
147ec_command(uint8_t cmd, uint8_t *dout, uint8_t dout_len,
148    uint8_t *dinp, uint8_t dinp_len)
149{
150	struct ec_softc *sc;
151	uint8_t *msg_dout;
152	uint8_t *msg_dinp;
153	int ret;
154	int i;
155
156	msg_dout = malloc(dout_len + 4, M_DEVBUF, M_NOWAIT);
157	msg_dinp = malloc(dinp_len + 4, M_DEVBUF, M_NOWAIT);
158
159	if (ec_sc == NULL)
160		return (-1);
161
162	sc = ec_sc;
163
164	msg_dout[0] = EC_CMD_VERSION0;
165	msg_dout[1] = cmd;
166	msg_dout[2] = dout_len;
167
168	for (i = 0; i < dout_len; i++) {
169		msg_dout[i + 3] = dout[i];
170	};
171
172	fill_checksum(msg_dout, dout_len + 3);
173
174	struct iic_msg msgs[] = {
175		{ 0x1e, IIC_M_WR, dout_len + 4, msg_dout, },
176		{ 0x1e, IIC_M_RD, dinp_len + 4, msg_dinp, },
177	};
178
179	ret = iicbus_transfer(sc->dev, msgs, 2);
180	if (ret != 0) {
181		device_printf(sc->dev, "i2c transfer returned %d\n", ret);
182		free(msg_dout, M_DEVBUF);
183		free(msg_dinp, M_DEVBUF);
184		return (-1);
185	}
186
187	for (i = 0; i < dinp_len; i++) {
188		dinp[i] = msg_dinp[i + 3];
189	};
190
191	free(msg_dout, M_DEVBUF);
192	free(msg_dinp, M_DEVBUF);
193	return (0);
194}
195
196int ec_hello(void)
197{
198	uint8_t data_in[4];
199	uint8_t data_out[4];
200
201	data_in[0] = 0x40;
202	data_in[1] = 0x30;
203	data_in[2] = 0x20;
204	data_in[3] = 0x10;
205
206	ec_command(EC_CMD_MKBP_STATE, data_in, 4,
207	    data_out, 4);
208
209	return (0);
210}
211
212static int
213ec_attach(device_t dev)
214{
215	struct ec_softc *sc;
216
217	sc = device_get_softc(dev);
218	sc->dev = dev;
219
220	ec_sc = sc;
221
222	/*
223	 * Claim the bus.
224	 *
225	 * We don't know cases when EC is master,
226	 * so hold the bus forever for us.
227	 *
228	 */
229
230	if (bus_claim(sc) != 0) {
231		return (ENXIO);
232	}
233
234	return (0);
235}
236
237static int
238ec_detach(device_t dev)
239{
240	struct ec_softc *sc;
241
242	sc = device_get_softc(dev);
243
244	bus_release(sc);
245
246	return (0);
247}
248
249static device_method_t ec_methods[] = {
250	DEVMETHOD(device_probe,		ec_probe),
251	DEVMETHOD(device_attach,	ec_attach),
252	DEVMETHOD(device_detach,	ec_detach),
253	{ 0, 0 }
254};
255
256static driver_t ec_driver = {
257	"chrome_ec",
258	ec_methods,
259	sizeof(struct ec_softc),
260};
261
262static devclass_t ec_devclass;
263
264DRIVER_MODULE(chrome_ec, iicbus, ec_driver, ec_devclass, 0, 0);
265MODULE_VERSION(chrome_ec, 1);
266MODULE_DEPEND(chrome_ec, iicbus, 1, 1, 1);
267