1// SPDX-License-Identifier: GPL-2.0
2/*
3 * The Gateworks System Controller (GSC) is a multi-function
4 * device designed for use in Gateworks Single Board Computers.
5 * The control interface is I2C, with an interrupt. The device supports
6 * system functions such as push-button monitoring, multiple ADC's for
7 * voltage and temperature monitoring, fan controller and watchdog monitor.
8 *
9 * Copyright (C) 2020 Gateworks Corporation
10 */
11
12#include <linux/device.h>
13#include <linux/i2c.h>
14#include <linux/interrupt.h>
15#include <linux/mfd/gsc.h>
16#include <linux/module.h>
17#include <linux/mutex.h>
18#include <linux/of.h>
19#include <linux/of_platform.h>
20#include <linux/platform_device.h>
21#include <linux/regmap.h>
22
23#include <asm/unaligned.h>
24
25/*
26 * The GSC suffers from an errata where occasionally during
27 * ADC cycles the chip can NAK I2C transactions. To ensure we have reliable
28 * register access we place retries around register access.
29 */
30#define I2C_RETRIES	3
31
32int gsc_write(void *context, unsigned int reg, unsigned int val)
33{
34	struct i2c_client *client = context;
35	int retry, ret;
36
37	for (retry = 0; retry < I2C_RETRIES; retry++) {
38		ret = i2c_smbus_write_byte_data(client, reg, val);
39		/*
40		 * -EAGAIN returned when the i2c host controller is busy
41		 * -EIO returned when i2c device is busy
42		 */
43		if (ret != -EAGAIN && ret != -EIO)
44			break;
45	}
46
47	return 0;
48}
49EXPORT_SYMBOL_GPL(gsc_write);
50
51int gsc_read(void *context, unsigned int reg, unsigned int *val)
52{
53	struct i2c_client *client = context;
54	int retry, ret;
55
56	for (retry = 0; retry < I2C_RETRIES; retry++) {
57		ret = i2c_smbus_read_byte_data(client, reg);
58		/*
59		 * -EAGAIN returned when the i2c host controller is busy
60		 * -EIO returned when i2c device is busy
61		 */
62		if (ret != -EAGAIN && ret != -EIO)
63			break;
64	}
65	*val = ret & 0xff;
66
67	return 0;
68}
69EXPORT_SYMBOL_GPL(gsc_read);
70
71/*
72 * gsc_powerdown - API to use GSC to power down board for a specific time
73 *
74 * secs - number of seconds to remain powered off
75 */
76static int gsc_powerdown(struct gsc_dev *gsc, unsigned long secs)
77{
78	int ret;
79	unsigned char regs[4];
80
81	dev_info(&gsc->i2c->dev, "GSC powerdown for %ld seconds\n",
82		 secs);
83
84	put_unaligned_le32(secs, regs);
85	ret = regmap_bulk_write(gsc->regmap, GSC_TIME_ADD, regs, 4);
86	if (ret)
87		return ret;
88
89	ret = regmap_update_bits(gsc->regmap, GSC_CTRL_1,
90				 BIT(GSC_CTRL_1_SLEEP_ADD),
91				 BIT(GSC_CTRL_1_SLEEP_ADD));
92	if (ret)
93		return ret;
94
95	ret = regmap_update_bits(gsc->regmap, GSC_CTRL_1,
96				 BIT(GSC_CTRL_1_SLEEP_ACTIVATE) |
97				 BIT(GSC_CTRL_1_SLEEP_ENABLE),
98				 BIT(GSC_CTRL_1_SLEEP_ACTIVATE) |
99				 BIT(GSC_CTRL_1_SLEEP_ENABLE));
100
101
102	return ret;
103}
104
105static ssize_t gsc_show(struct device *dev, struct device_attribute *attr,
106			char *buf)
107{
108	struct gsc_dev *gsc = dev_get_drvdata(dev);
109	const char *name = attr->attr.name;
110	int rz = 0;
111
112	if (strcasecmp(name, "fw_version") == 0)
113		rz = sprintf(buf, "%d\n", gsc->fwver);
114	else if (strcasecmp(name, "fw_crc") == 0)
115		rz = sprintf(buf, "0x%04x\n", gsc->fwcrc);
116	else
117		dev_err(dev, "invalid command: '%s'\n", name);
118
119	return rz;
120}
121
122static ssize_t gsc_store(struct device *dev, struct device_attribute *attr,
123			 const char *buf, size_t count)
124{
125	struct gsc_dev *gsc = dev_get_drvdata(dev);
126	const char *name = attr->attr.name;
127	long value;
128
129	if (strcasecmp(name, "powerdown") == 0) {
130		if (kstrtol(buf, 0, &value) == 0)
131			gsc_powerdown(gsc, value);
132	} else {
133		dev_err(dev, "invalid command: '%s\n", name);
134	}
135
136	return count;
137}
138
139static struct device_attribute attr_fwver =
140	__ATTR(fw_version, 0440, gsc_show, NULL);
141static struct device_attribute attr_fwcrc =
142	__ATTR(fw_crc, 0440, gsc_show, NULL);
143static struct device_attribute attr_pwrdown =
144	__ATTR(powerdown, 0220, NULL, gsc_store);
145
146static struct attribute *gsc_attrs[] = {
147	&attr_fwver.attr,
148	&attr_fwcrc.attr,
149	&attr_pwrdown.attr,
150	NULL,
151};
152
153static struct attribute_group attr_group = {
154	.attrs = gsc_attrs,
155};
156
157static const struct of_device_id gsc_of_match[] = {
158	{ .compatible = "gw,gsc", },
159	{ }
160};
161MODULE_DEVICE_TABLE(of, gsc_of_match);
162
163static struct regmap_bus gsc_regmap_bus = {
164	.reg_read = gsc_read,
165	.reg_write = gsc_write,
166};
167
168static const struct regmap_config gsc_regmap_config = {
169	.reg_bits = 8,
170	.val_bits = 8,
171	.cache_type = REGCACHE_NONE,
172	.max_register = GSC_WP,
173};
174
175static const struct regmap_irq gsc_irqs[] = {
176	REGMAP_IRQ_REG(GSC_IRQ_PB, 0, BIT(GSC_IRQ_PB)),
177	REGMAP_IRQ_REG(GSC_IRQ_KEY_ERASED, 0, BIT(GSC_IRQ_KEY_ERASED)),
178	REGMAP_IRQ_REG(GSC_IRQ_EEPROM_WP, 0, BIT(GSC_IRQ_EEPROM_WP)),
179	REGMAP_IRQ_REG(GSC_IRQ_RESV, 0, BIT(GSC_IRQ_RESV)),
180	REGMAP_IRQ_REG(GSC_IRQ_GPIO, 0, BIT(GSC_IRQ_GPIO)),
181	REGMAP_IRQ_REG(GSC_IRQ_TAMPER, 0, BIT(GSC_IRQ_TAMPER)),
182	REGMAP_IRQ_REG(GSC_IRQ_WDT_TIMEOUT, 0, BIT(GSC_IRQ_WDT_TIMEOUT)),
183	REGMAP_IRQ_REG(GSC_IRQ_SWITCH_HOLD, 0, BIT(GSC_IRQ_SWITCH_HOLD)),
184};
185
186static const struct regmap_irq_chip gsc_irq_chip = {
187	.name = "gateworks-gsc",
188	.irqs = gsc_irqs,
189	.num_irqs = ARRAY_SIZE(gsc_irqs),
190	.num_regs = 1,
191	.status_base = GSC_IRQ_STATUS,
192	.unmask_base = GSC_IRQ_ENABLE,
193	.ack_base = GSC_IRQ_STATUS,
194	.ack_invert = true,
195};
196
197static int gsc_probe(struct i2c_client *client)
198{
199	struct device *dev = &client->dev;
200	struct gsc_dev *gsc;
201	struct regmap_irq_chip_data *irq_data;
202	int ret;
203	unsigned int reg;
204
205	gsc = devm_kzalloc(dev, sizeof(*gsc), GFP_KERNEL);
206	if (!gsc)
207		return -ENOMEM;
208
209	gsc->dev = &client->dev;
210	gsc->i2c = client;
211	i2c_set_clientdata(client, gsc);
212
213	gsc->regmap = devm_regmap_init(dev, &gsc_regmap_bus, client,
214				       &gsc_regmap_config);
215	if (IS_ERR(gsc->regmap))
216		return PTR_ERR(gsc->regmap);
217
218	if (regmap_read(gsc->regmap, GSC_FW_VER, &reg))
219		return -EIO;
220	gsc->fwver = reg;
221
222	regmap_read(gsc->regmap, GSC_FW_CRC, &reg);
223	gsc->fwcrc = reg;
224	regmap_read(gsc->regmap, GSC_FW_CRC + 1, &reg);
225	gsc->fwcrc |= reg << 8;
226
227	gsc->i2c_hwmon = devm_i2c_new_dummy_device(dev, client->adapter,
228						   GSC_HWMON);
229	if (IS_ERR(gsc->i2c_hwmon)) {
230		dev_err(dev, "Failed to allocate I2C device for HWMON\n");
231		return PTR_ERR(gsc->i2c_hwmon);
232	}
233
234	ret = devm_regmap_add_irq_chip(dev, gsc->regmap, client->irq,
235				       IRQF_ONESHOT | IRQF_SHARED |
236				       IRQF_TRIGGER_LOW, 0,
237				       &gsc_irq_chip, &irq_data);
238	if (ret)
239		return ret;
240
241	dev_info(dev, "Gateworks System Controller v%d: fw 0x%04x\n",
242		 gsc->fwver, gsc->fwcrc);
243
244	ret = sysfs_create_group(&dev->kobj, &attr_group);
245	if (ret)
246		dev_err(dev, "failed to create sysfs attrs\n");
247
248	ret = devm_of_platform_populate(dev);
249	if (ret) {
250		sysfs_remove_group(&dev->kobj, &attr_group);
251		return ret;
252	}
253
254	return 0;
255}
256
257static void gsc_remove(struct i2c_client *client)
258{
259	sysfs_remove_group(&client->dev.kobj, &attr_group);
260}
261
262static struct i2c_driver gsc_driver = {
263	.driver = {
264		.name	= "gateworks-gsc",
265		.of_match_table = gsc_of_match,
266	},
267	.probe		= gsc_probe,
268	.remove		= gsc_remove,
269};
270module_i2c_driver(gsc_driver);
271
272MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>");
273MODULE_DESCRIPTION("I2C Core interface for GSC");
274MODULE_LICENSE("GPL v2");
275