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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 .mask_base = GSC_IRQ_ENABLE,
193 .mask_invert = true,
194 .ack_base = GSC_IRQ_STATUS,
195 .ack_invert = true,
196};
197
198static int gsc_probe(struct i2c_client *client)
199{
200 struct device *dev = &client->dev;
201 struct gsc_dev *gsc;
202 struct regmap_irq_chip_data *irq_data;
203 int ret;
204 unsigned int reg;
205
206 gsc = devm_kzalloc(dev, sizeof(*gsc), GFP_KERNEL);
207 if (!gsc)
208 return -ENOMEM;
209
210 gsc->dev = &client->dev;
211 gsc->i2c = client;
212 i2c_set_clientdata(client, gsc);
213
214 gsc->regmap = devm_regmap_init(dev, &gsc_regmap_bus, client,
215 &gsc_regmap_config);
216 if (IS_ERR(gsc->regmap))
217 return PTR_ERR(gsc->regmap);
218
219 if (regmap_read(gsc->regmap, GSC_FW_VER, ®))
220 return -EIO;
221 gsc->fwver = reg;
222
223 regmap_read(gsc->regmap, GSC_FW_CRC, ®);
224 gsc->fwcrc = reg;
225 regmap_read(gsc->regmap, GSC_FW_CRC + 1, ®);
226 gsc->fwcrc |= reg << 8;
227
228 gsc->i2c_hwmon = devm_i2c_new_dummy_device(dev, client->adapter,
229 GSC_HWMON);
230 if (IS_ERR(gsc->i2c_hwmon)) {
231 dev_err(dev, "Failed to allocate I2C device for HWMON\n");
232 return PTR_ERR(gsc->i2c_hwmon);
233 }
234
235 ret = devm_regmap_add_irq_chip(dev, gsc->regmap, client->irq,
236 IRQF_ONESHOT | IRQF_SHARED |
237 IRQF_TRIGGER_FALLING, 0,
238 &gsc_irq_chip, &irq_data);
239 if (ret)
240 return ret;
241
242 dev_info(dev, "Gateworks System Controller v%d: fw 0x%04x\n",
243 gsc->fwver, gsc->fwcrc);
244
245 ret = sysfs_create_group(&dev->kobj, &attr_group);
246 if (ret)
247 dev_err(dev, "failed to create sysfs attrs\n");
248
249 ret = devm_of_platform_populate(dev);
250 if (ret) {
251 sysfs_remove_group(&dev->kobj, &attr_group);
252 return ret;
253 }
254
255 return 0;
256}
257
258static int gsc_remove(struct i2c_client *client)
259{
260 sysfs_remove_group(&client->dev.kobj, &attr_group);
261
262 return 0;
263}
264
265static struct i2c_driver gsc_driver = {
266 .driver = {
267 .name = "gateworks-gsc",
268 .of_match_table = gsc_of_match,
269 },
270 .probe_new = gsc_probe,
271 .remove = gsc_remove,
272};
273module_i2c_driver(gsc_driver);
274
275MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>");
276MODULE_DESCRIPTION("I2C Core interface for GSC");
277MODULE_LICENSE("GPL v2");