1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Chrome OS EC MEMS Sensor Hub driver.
4  *
5  * Copyright 2019 Google LLC
6  */
7 
8 #ifndef __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H
9 #define __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H
10 
11 #include <linux/ktime.h>
12 #include <linux/mutex.h>
13 #include <linux/notifier.h>
14 #include <linux/platform_data/cros_ec_commands.h>
15 
16 struct iio_dev;
17 
18 /**
19  * struct cros_ec_sensor_platform - ChromeOS EC sensor platform information.
20  * @sensor_num: Id of the sensor, as reported by the EC.
21  */
22 struct cros_ec_sensor_platform {
23 	u8 sensor_num;
24 };
25 
26 /**
27  * typedef cros_ec_sensorhub_push_data_cb_t - Callback function to send datum
28  *					      to specific sensors.
29  *
30  * @indio_dev: The IIO device that will process the sample.
31  * @data: Vector array of the ring sample.
32  * @timestamp: Timestamp in host timespace when the sample was acquired by
33  *             the EC.
34  */
35 typedef int (*cros_ec_sensorhub_push_data_cb_t)(struct iio_dev *indio_dev,
36 						s16 *data,
37 						s64 timestamp);
38 
39 struct cros_ec_sensorhub_sensor_push_data {
40 	struct iio_dev *indio_dev;
41 	cros_ec_sensorhub_push_data_cb_t push_data_cb;
42 };
43 
44 enum {
45 	CROS_EC_SENSOR_LAST_TS,
46 	CROS_EC_SENSOR_NEW_TS,
47 	CROS_EC_SENSOR_ALL_TS
48 };
49 
50 struct cros_ec_sensors_ring_sample {
51 	u8  sensor_id;
52 	u8  flag;
53 	s16 vector[3];
54 	s64 timestamp;
55 } __packed;
56 
57 /* State used for cros_ec_ring_fix_overflow */
58 struct cros_ec_sensors_ec_overflow_state {
59 	s64 offset;
60 	s64 last;
61 };
62 
63 /* Length of the filter, how long to remember entries for */
64 #define CROS_EC_SENSORHUB_TS_HISTORY_SIZE 64
65 
66 /**
67  * struct cros_ec_sensors_ts_filter_state - Timestamp filetr state.
68  *
69  * @x_offset: x is EC interrupt time. x_offset its last value.
70  * @y_offset: y is the difference between AP and EC time, y_offset its last
71  *            value.
72  * @x_history: The past history of x, relative to x_offset.
73  * @y_history: The past history of y, relative to y_offset.
74  * @m_history: rate between y and x.
75  * @history_len: Amount of valid historic data in the arrays.
76  * @temp_buf: Temporary buffer used when updating the filter.
77  * @median_m: median value of m_history
78  * @median_error: final error to apply to AP interrupt timestamp to get the
79  *                "true timestamp" the event occurred.
80  */
81 struct cros_ec_sensors_ts_filter_state {
82 	s64 x_offset, y_offset;
83 	s64 x_history[CROS_EC_SENSORHUB_TS_HISTORY_SIZE];
84 	s64 y_history[CROS_EC_SENSORHUB_TS_HISTORY_SIZE];
85 	s64 m_history[CROS_EC_SENSORHUB_TS_HISTORY_SIZE];
86 	int history_len;
87 
88 	s64 temp_buf[CROS_EC_SENSORHUB_TS_HISTORY_SIZE];
89 
90 	s64 median_m;
91 	s64 median_error;
92 };
93 
94 /* struct cros_ec_sensors_ts_batch_state - State of batch of a single sensor.
95  *
96  * Use to store information to batch data using median fileter information.
97  *
98  * @penul_ts: last but one batch timestamp (penultimate timestamp).
99  *	      Used for timestamp spreading calculations
100  *	      when a batch shows up.
101  * @penul_len: last but one batch length.
102  * @last_ts: Last batch timestam.
103  * @last_len: Last batch length.
104  * @newest_sensor_event: Last sensor timestamp.
105  */
106 struct cros_ec_sensors_ts_batch_state {
107 	s64 penul_ts;
108 	int penul_len;
109 	s64 last_ts;
110 	int last_len;
111 	s64 newest_sensor_event;
112 };
113 
114 /*
115  * struct cros_ec_sensorhub - Sensor Hub device data.
116  *
117  * @dev: Device object, mostly used for logging.
118  * @ec: Embedded Controller where the hub is located.
119  * @sensor_num: Number of MEMS sensors present in the EC.
120  * @msg: Structure to send FIFO requests.
121  * @params: Pointer to parameters in msg.
122  * @resp: Pointer to responses in msg.
123  * @cmd_lock : Lock for sending msg.
124  * @notifier: Notifier to kick the FIFO interrupt.
125  * @ring: Preprocessed ring to store events.
126  * @fifo_timestamp: Array for event timestamp and spreading.
127  * @fifo_info: Copy of FIFO information coming from the EC.
128  * @fifo_size: Size of the ring.
129  * @batch_state: Per sensor information of the last batches received.
130  * @overflow_a: For handling timestamp overflow for a time (sensor events)
131  * @overflow_b: For handling timestamp overflow for b time (ec interrupts)
132  * @filter: Medium fileter structure.
133  * @tight_timestamps: Set to truen when EC support tight timestamping:
134  *		      The timestamps reported from the EC have low jitter.
135  *		      Timestamps also come before every sample. Set either
136  *		      by feature bits coming from the EC or userspace.
137  * @future_timestamp_count: Statistics used to compute shaved time.
138  *			    This occurs when timestamp interpolation from EC
139  *			    time to AP time accidentally puts timestamps in
140  *			    the future. These timestamps are clamped to
141  *			    `now` and these count/total_ns maintain the
142  *			    statistics for how much time was removed in a
143  *			    given period.
144  * @future_timestamp_total_ns: Total amount of time shaved.
145  * @push_data: Array of callback to send datums to iio sensor object.
146  */
147 struct cros_ec_sensorhub {
148 	struct device *dev;
149 	struct cros_ec_dev *ec;
150 	int sensor_num;
151 
152 	struct cros_ec_command *msg;
153 	struct ec_params_motion_sense *params;
154 	struct ec_response_motion_sense *resp;
155 	struct mutex cmd_lock;  /* Lock for protecting msg structure. */
156 
157 	struct notifier_block notifier;
158 
159 	struct cros_ec_sensors_ring_sample *ring;
160 
161 	ktime_t fifo_timestamp[CROS_EC_SENSOR_ALL_TS];
162 	struct ec_response_motion_sense_fifo_info *fifo_info;
163 	int fifo_size;
164 
165 	struct cros_ec_sensors_ts_batch_state *batch_state;
166 
167 	struct cros_ec_sensors_ec_overflow_state overflow_a;
168 	struct cros_ec_sensors_ec_overflow_state overflow_b;
169 
170 	struct cros_ec_sensors_ts_filter_state filter;
171 
172 	int tight_timestamps;
173 
174 	s32 future_timestamp_count;
175 	s64 future_timestamp_total_ns;
176 
177 	struct cros_ec_sensorhub_sensor_push_data *push_data;
178 };
179 
180 int cros_ec_sensorhub_register_push_data(struct cros_ec_sensorhub *sensorhub,
181 					 u8 sensor_num,
182 					 struct iio_dev *indio_dev,
183 					 cros_ec_sensorhub_push_data_cb_t cb);
184 
185 void cros_ec_sensorhub_unregister_push_data(struct cros_ec_sensorhub *sensorhub,
186 					    u8 sensor_num);
187 
188 int cros_ec_sensorhub_ring_allocate(struct cros_ec_sensorhub *sensorhub);
189 int cros_ec_sensorhub_ring_add(struct cros_ec_sensorhub *sensorhub);
190 void cros_ec_sensorhub_ring_remove(void *arg);
191 int cros_ec_sensorhub_ring_fifo_enable(struct cros_ec_sensorhub *sensorhub,
192 				       bool on);
193 
194 #endif   /* __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H */
195