1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * AC driver for 7th-generation Microsoft Surface devices via Surface System
4  * Aggregator Module (SSAM).
5  *
6  * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
7  */
8 
9 #include <asm/unaligned.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/mutex.h>
13 #include <linux/power_supply.h>
14 #include <linux/types.h>
15 
16 #include <linux/surface_aggregator/device.h>
17 
18 
19 /* -- SAM interface. -------------------------------------------------------- */
20 
21 enum sam_event_cid_bat {
22 	SAM_EVENT_CID_BAT_ADP   = 0x17,
23 };
24 
25 enum sam_battery_sta {
26 	SAM_BATTERY_STA_OK      = 0x0f,
27 	SAM_BATTERY_STA_PRESENT	= 0x10,
28 };
29 
30 /* Get battery status (_STA). */
31 SSAM_DEFINE_SYNC_REQUEST_CL_R(ssam_bat_get_sta, __le32, {
32 	.target_category = SSAM_SSH_TC_BAT,
33 	.command_id      = 0x01,
34 });
35 
36 /* Get platform power source for battery (_PSR / DPTF PSRC). */
37 SSAM_DEFINE_SYNC_REQUEST_CL_R(ssam_bat_get_psrc, __le32, {
38 	.target_category = SSAM_SSH_TC_BAT,
39 	.command_id      = 0x0d,
40 });
41 
42 
43 /* -- Device structures. ---------------------------------------------------- */
44 
45 struct spwr_psy_properties {
46 	const char *name;
47 	struct ssam_event_registry registry;
48 };
49 
50 struct spwr_ac_device {
51 	struct ssam_device *sdev;
52 
53 	char name[32];
54 	struct power_supply *psy;
55 	struct power_supply_desc psy_desc;
56 
57 	struct ssam_event_notifier notif;
58 
59 	struct mutex lock;  /* Guards access to state below. */
60 
61 	__le32 state;
62 };
63 
64 
65 /* -- State management. ----------------------------------------------------- */
66 
spwr_ac_update_unlocked(struct spwr_ac_device * ac)67 static int spwr_ac_update_unlocked(struct spwr_ac_device *ac)
68 {
69 	__le32 old = ac->state;
70 	int status;
71 
72 	lockdep_assert_held(&ac->lock);
73 
74 	status = ssam_retry(ssam_bat_get_psrc, ac->sdev, &ac->state);
75 	if (status < 0)
76 		return status;
77 
78 	return old != ac->state;
79 }
80 
spwr_ac_update(struct spwr_ac_device * ac)81 static int spwr_ac_update(struct spwr_ac_device *ac)
82 {
83 	int status;
84 
85 	mutex_lock(&ac->lock);
86 	status = spwr_ac_update_unlocked(ac);
87 	mutex_unlock(&ac->lock);
88 
89 	return status;
90 }
91 
spwr_ac_recheck(struct spwr_ac_device * ac)92 static int spwr_ac_recheck(struct spwr_ac_device *ac)
93 {
94 	int status;
95 
96 	status = spwr_ac_update(ac);
97 	if (status > 0)
98 		power_supply_changed(ac->psy);
99 
100 	return status >= 0 ? 0 : status;
101 }
102 
spwr_notify_ac(struct ssam_event_notifier * nf,const struct ssam_event * event)103 static u32 spwr_notify_ac(struct ssam_event_notifier *nf, const struct ssam_event *event)
104 {
105 	struct spwr_ac_device *ac;
106 	int status;
107 
108 	ac = container_of(nf, struct spwr_ac_device, notif);
109 
110 	dev_dbg(&ac->sdev->dev, "power event (cid = %#04x, iid = %#04x, tid = %#04x)\n",
111 		event->command_id, event->instance_id, event->target_id);
112 
113 	/*
114 	 * Allow events of all targets/instances here. Global adapter status
115 	 * seems to be handled via target=1 and instance=1, but events are
116 	 * reported on all targets/instances in use.
117 	 *
118 	 * While it should be enough to just listen on 1/1, listen everywhere to
119 	 * make sure we don't miss anything.
120 	 */
121 
122 	switch (event->command_id) {
123 	case SAM_EVENT_CID_BAT_ADP:
124 		status = spwr_ac_recheck(ac);
125 		return ssam_notifier_from_errno(status) | SSAM_NOTIF_HANDLED;
126 
127 	default:
128 		return 0;
129 	}
130 }
131 
132 
133 /* -- Properties. ----------------------------------------------------------- */
134 
135 static const enum power_supply_property spwr_ac_props[] = {
136 	POWER_SUPPLY_PROP_ONLINE,
137 };
138 
spwr_ac_get_property(struct power_supply * psy,enum power_supply_property psp,union power_supply_propval * val)139 static int spwr_ac_get_property(struct power_supply *psy, enum power_supply_property psp,
140 				union power_supply_propval *val)
141 {
142 	struct spwr_ac_device *ac = power_supply_get_drvdata(psy);
143 	int status;
144 
145 	mutex_lock(&ac->lock);
146 
147 	status = spwr_ac_update_unlocked(ac);
148 	if (status)
149 		goto out;
150 
151 	switch (psp) {
152 	case POWER_SUPPLY_PROP_ONLINE:
153 		val->intval = !!le32_to_cpu(ac->state);
154 		break;
155 
156 	default:
157 		status = -EINVAL;
158 		goto out;
159 	}
160 
161 out:
162 	mutex_unlock(&ac->lock);
163 	return status;
164 }
165 
166 
167 /* -- Device setup. --------------------------------------------------------- */
168 
169 static char *battery_supplied_to[] = {
170 	"BAT1",
171 	"BAT2",
172 };
173 
spwr_ac_init(struct spwr_ac_device * ac,struct ssam_device * sdev,struct ssam_event_registry registry,const char * name)174 static void spwr_ac_init(struct spwr_ac_device *ac, struct ssam_device *sdev,
175 			 struct ssam_event_registry registry, const char *name)
176 {
177 	mutex_init(&ac->lock);
178 	strncpy(ac->name, name, ARRAY_SIZE(ac->name) - 1);
179 
180 	ac->sdev = sdev;
181 
182 	ac->notif.base.priority = 1;
183 	ac->notif.base.fn = spwr_notify_ac;
184 	ac->notif.event.reg = registry;
185 	ac->notif.event.id.target_category = sdev->uid.category;
186 	ac->notif.event.id.instance = 0;
187 	ac->notif.event.mask = SSAM_EVENT_MASK_NONE;
188 	ac->notif.event.flags = SSAM_EVENT_SEQUENCED;
189 
190 	ac->psy_desc.name = ac->name;
191 	ac->psy_desc.type = POWER_SUPPLY_TYPE_MAINS;
192 	ac->psy_desc.properties = spwr_ac_props;
193 	ac->psy_desc.num_properties = ARRAY_SIZE(spwr_ac_props);
194 	ac->psy_desc.get_property = spwr_ac_get_property;
195 }
196 
spwr_ac_register(struct spwr_ac_device * ac)197 static int spwr_ac_register(struct spwr_ac_device *ac)
198 {
199 	struct power_supply_config psy_cfg = {};
200 	__le32 sta;
201 	int status;
202 
203 	/* Make sure the device is there and functioning properly. */
204 	status = ssam_retry(ssam_bat_get_sta, ac->sdev, &sta);
205 	if (status)
206 		return status;
207 
208 	if ((le32_to_cpu(sta) & SAM_BATTERY_STA_OK) != SAM_BATTERY_STA_OK)
209 		return -ENODEV;
210 
211 	psy_cfg.drv_data = ac;
212 	psy_cfg.supplied_to = battery_supplied_to;
213 	psy_cfg.num_supplicants = ARRAY_SIZE(battery_supplied_to);
214 
215 	ac->psy = devm_power_supply_register(&ac->sdev->dev, &ac->psy_desc, &psy_cfg);
216 	if (IS_ERR(ac->psy))
217 		return PTR_ERR(ac->psy);
218 
219 	return ssam_device_notifier_register(ac->sdev, &ac->notif);
220 }
221 
222 
223 /* -- Driver setup. --------------------------------------------------------- */
224 
surface_ac_resume(struct device * dev)225 static int __maybe_unused surface_ac_resume(struct device *dev)
226 {
227 	return spwr_ac_recheck(dev_get_drvdata(dev));
228 }
229 static SIMPLE_DEV_PM_OPS(surface_ac_pm_ops, NULL, surface_ac_resume);
230 
surface_ac_probe(struct ssam_device * sdev)231 static int surface_ac_probe(struct ssam_device *sdev)
232 {
233 	const struct spwr_psy_properties *p;
234 	struct spwr_ac_device *ac;
235 
236 	p = ssam_device_get_match_data(sdev);
237 	if (!p)
238 		return -ENODEV;
239 
240 	ac = devm_kzalloc(&sdev->dev, sizeof(*ac), GFP_KERNEL);
241 	if (!ac)
242 		return -ENOMEM;
243 
244 	spwr_ac_init(ac, sdev, p->registry, p->name);
245 	ssam_device_set_drvdata(sdev, ac);
246 
247 	return spwr_ac_register(ac);
248 }
249 
surface_ac_remove(struct ssam_device * sdev)250 static void surface_ac_remove(struct ssam_device *sdev)
251 {
252 	struct spwr_ac_device *ac = ssam_device_get_drvdata(sdev);
253 
254 	ssam_device_notifier_unregister(sdev, &ac->notif);
255 }
256 
257 static const struct spwr_psy_properties spwr_psy_props_adp1 = {
258 	.name = "ADP1",
259 	.registry = SSAM_EVENT_REGISTRY_SAM,
260 };
261 
262 static const struct ssam_device_id surface_ac_match[] = {
263 	{ SSAM_SDEV(BAT, SAM, 0x01, 0x01), (unsigned long)&spwr_psy_props_adp1 },
264 	{ },
265 };
266 MODULE_DEVICE_TABLE(ssam, surface_ac_match);
267 
268 static struct ssam_device_driver surface_ac_driver = {
269 	.probe = surface_ac_probe,
270 	.remove = surface_ac_remove,
271 	.match_table = surface_ac_match,
272 	.driver = {
273 		.name = "surface_ac",
274 		.pm = &surface_ac_pm_ops,
275 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
276 	},
277 };
278 module_ssam_device_driver(surface_ac_driver);
279 
280 MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
281 MODULE_DESCRIPTION("AC driver for Surface System Aggregator Module");
282 MODULE_LICENSE("GPL");
283