1 /*
2 * (C) Copyright 2020 Rockchip Electronics Co., Ltd
3 *
4 * SPDX-License-Identifier: GPL-2.0+
5 */
6
7 #include <common.h>
8 #include <adc.h>
9 #include <div64.h>
10 #include <fdtdec.h>
11 #include <dm/uclass.h>
12
13 DECLARE_GLOBAL_DATA_PTR;
14
adc_raw_to_mV(struct udevice * dev,unsigned int raw,int * mV)15 static int adc_raw_to_mV(struct udevice *dev, unsigned int raw, int *mV)
16 {
17 unsigned int data_mask;
18 int ret, vref = 1800000;
19 u64 raw64 = raw;
20
21 ret = adc_data_mask(dev, &data_mask);
22 if (ret)
23 return ret;
24
25 raw64 *= vref;
26 do_div(raw64, data_mask);
27 *mV = raw64;
28
29 return 0;
30 }
31
key_read(int code)32 int key_read(int code)
33 {
34 const void *fdt_blob = gd->fdt_blob;
35 struct udevice *dev;
36 int adc_node, offset;
37 int t, down_threshold = -1, up_threshold;
38 int ret, num = 0, volt_margin = 150000; /* will be div 2 */
39 int mV, cd, voltage = -1;
40 int min, max;
41 u32 chn[2], adc;
42
43 ret = uclass_get_device_by_name(UCLASS_ADC, "saradc", &dev);
44 if (ret)
45 ret = uclass_get_device_by_name(UCLASS_ADC, "adc", &dev);
46 if (ret) {
47 debug("No saradc device, ret=%d\n", ret);
48 return 0;
49 }
50
51 adc_node = fdt_node_offset_by_compatible(fdt_blob, 0, "adc-keys");
52 if (adc_node < 0) {
53 debug("No 'adc-keys' node, ret=%d\n", adc_node);
54 return 0;
55 }
56
57 ret = fdtdec_get_int_array(fdt_blob, adc_node, "io-channels",
58 chn, ARRAY_SIZE(chn));
59 if (ret) {
60 debug("Can't read 'io-channels', ret=%d\n", ret);
61 return 0;
62 }
63
64 up_threshold = fdtdec_get_int(fdt_blob, adc_node,
65 "keyup-threshold-microvolt", -ENODATA);
66 if (up_threshold < 0) {
67 debug("Can't read 'keyup-threshold-microvolt'\n");
68 return 0;
69 }
70
71 /* find the expected key-code */
72 for (offset = fdt_first_subnode(fdt_blob, adc_node);
73 offset >= 0;
74 offset = fdt_next_subnode(fdt_blob, offset)) {
75 cd = fdtdec_get_int(fdt_blob, offset, "linux,code", -ENODATA);
76 if (cd < 0) {
77 debug("Can't read 'linux,code', ret=%d\n", cd);
78 return 0;
79 }
80
81 if (cd == code) {
82 voltage = fdtdec_get_int(fdt_blob, offset,
83 "press-threshold-microvolt", -ENODATA);
84 if (voltage < 0) {
85 debug("Can't read 'press-threshold-microvolt'\n");
86 return 0;
87 }
88 break;
89 }
90 }
91
92 if (voltage < 0)
93 return 0;
94
95 for (offset = fdt_first_subnode(fdt_blob, adc_node);
96 offset >= 0;
97 offset = fdt_next_subnode(fdt_blob, offset)) {
98 t = fdtdec_get_int(fdt_blob, offset,
99 "press-threshold-microvolt", -ENODATA);
100 if (t < 0) {
101 debug("Can't read 'press-threshold-microvolt'\n");
102 return 0;
103 }
104
105 if (t > voltage && t < up_threshold)
106 up_threshold = t;
107 else if (t < voltage && t > down_threshold)
108 down_threshold = t;
109 num++;
110 }
111
112 /* although one node only, it doesn't mean only one key on hardware */
113 if (num == 1) {
114 down_threshold = voltage - volt_margin;
115 up_threshold = voltage + volt_margin;
116 }
117
118 /*
119 * Define the voltage range such that the button is only pressed
120 * when the voltage is closest to its own press-threshold-microvolt
121 */
122 if (down_threshold < 0)
123 min = 0;
124 else
125 min = down_threshold + (voltage - down_threshold) / 2;
126
127 max = voltage + (up_threshold - voltage) / 2;
128
129 /* now, read key status */
130 ret = adc_channel_single_shot("saradc", chn[1], &adc);
131 if (ret)
132 ret = adc_channel_single_shot("adc", chn[1], &adc);
133 if (ret) {
134 debug("Failed to read adc%d, ret=%d\n", chn[1], ret);
135 return 0;
136 }
137
138 ret = adc_raw_to_mV(dev, adc, &mV);
139 if (ret) {
140 debug("Failed to convert adc to mV, ret=%d\n", ret);
141 return 0;
142 }
143
144 debug("key[%d] <%d, %d, %d>: adc=%d -> mV=%d\n",
145 code, min, voltage, max, adc, mV);
146
147 return (mV <= max && mV >= min);
148 }
149
150