xref: /openbmc/linux/drivers/mfd/gateworks-gsc.c (revision 9816d859)
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 
gsc_write(void * context,unsigned int reg,unsigned int val)32 int 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 }
49 EXPORT_SYMBOL_GPL(gsc_write);
50 
gsc_read(void * context,unsigned int reg,unsigned int * val)51 int 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 }
69 EXPORT_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  */
gsc_powerdown(struct gsc_dev * gsc,unsigned long secs)76 static 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 
gsc_show(struct device * dev,struct device_attribute * attr,char * buf)105 static 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 
gsc_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)122 static 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 
139 static struct device_attribute attr_fwver =
140 	__ATTR(fw_version, 0440, gsc_show, NULL);
141 static struct device_attribute attr_fwcrc =
142 	__ATTR(fw_crc, 0440, gsc_show, NULL);
143 static struct device_attribute attr_pwrdown =
144 	__ATTR(powerdown, 0220, NULL, gsc_store);
145 
146 static struct attribute *gsc_attrs[] = {
147 	&attr_fwver.attr,
148 	&attr_fwcrc.attr,
149 	&attr_pwrdown.attr,
150 	NULL,
151 };
152 
153 static struct attribute_group attr_group = {
154 	.attrs = gsc_attrs,
155 };
156 
157 static const struct of_device_id gsc_of_match[] = {
158 	{ .compatible = "gw,gsc", },
159 	{ }
160 };
161 MODULE_DEVICE_TABLE(of, gsc_of_match);
162 
163 static struct regmap_bus gsc_regmap_bus = {
164 	.reg_read = gsc_read,
165 	.reg_write = gsc_write,
166 };
167 
168 static 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 
175 static 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 
186 static 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 
gsc_probe(struct i2c_client * client)197 static 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 
gsc_remove(struct i2c_client * client)257 static void gsc_remove(struct i2c_client *client)
258 {
259 	sysfs_remove_group(&client->dev.kobj, &attr_group);
260 }
261 
262 static 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 };
270 module_i2c_driver(gsc_driver);
271 
272 MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>");
273 MODULE_DESCRIPTION("I2C Core interface for GSC");
274 MODULE_LICENSE("GPL v2");
275