1 /*
2  *  Copyright (C) 2013 Daniel Tang <tangrs@tangrs.id.au>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2, as
6  * published by the Free Software Foundation.
7  */
8 
9 #include <linux/input/matrix_keypad.h>
10 #include <linux/platform_device.h>
11 #include <linux/interrupt.h>
12 #include <linux/io.h>
13 #include <linux/delay.h>
14 #include <linux/input.h>
15 #include <linux/slab.h>
16 #include <linux/clk.h>
17 #include <linux/module.h>
18 #include <linux/of.h>
19 
20 #define KEYPAD_SCAN_MODE	0x00
21 #define KEYPAD_CNTL		0x04
22 #define KEYPAD_INT		0x08
23 #define KEYPAD_INTMSK		0x0C
24 
25 #define KEYPAD_DATA		0x10
26 #define KEYPAD_GPIO		0x30
27 
28 #define KEYPAD_UNKNOWN_INT	0x40
29 #define KEYPAD_UNKNOWN_INT_STS	0x44
30 
31 #define KEYPAD_BITMASK_COLS	11
32 #define KEYPAD_BITMASK_ROWS	8
33 
34 struct nspire_keypad {
35 	void __iomem *reg_base;
36 	u32 int_mask;
37 
38 	struct input_dev *input;
39 	struct clk *clk;
40 
41 	struct matrix_keymap_data *keymap;
42 	int row_shift;
43 
44 	/* Maximum delay estimated assuming 33MHz APB */
45 	u32 scan_interval;	/* In microseconds (~2000us max) */
46 	u32 row_delay;		/* In microseconds (~500us max) */
47 
48 	u16 state[KEYPAD_BITMASK_ROWS];
49 
50 	bool active_low;
51 };
52 
53 static irqreturn_t nspire_keypad_irq(int irq, void *dev_id)
54 {
55 	struct nspire_keypad *keypad = dev_id;
56 	struct input_dev *input = keypad->input;
57 	unsigned short *keymap = input->keycode;
58 	unsigned int code;
59 	int row, col;
60 	u32 int_sts;
61 	u16 state[8];
62 	u16 bits, changed;
63 
64 	int_sts = readl(keypad->reg_base + KEYPAD_INT) & keypad->int_mask;
65 	if (!int_sts)
66 		return IRQ_NONE;
67 
68 	memcpy_fromio(state, keypad->reg_base + KEYPAD_DATA, sizeof(state));
69 
70 	for (row = 0; row < KEYPAD_BITMASK_ROWS; row++) {
71 		bits = state[row];
72 		if (keypad->active_low)
73 			bits = ~bits;
74 
75 		changed = bits ^ keypad->state[row];
76 		if (!changed)
77 			continue;
78 
79 		keypad->state[row] = bits;
80 
81 		for (col = 0; col < KEYPAD_BITMASK_COLS; col++) {
82 			if (!(changed & (1U << col)))
83 				continue;
84 
85 			code = MATRIX_SCAN_CODE(row, col, keypad->row_shift);
86 			input_event(input, EV_MSC, MSC_SCAN, code);
87 			input_report_key(input, keymap[code],
88 					 bits & (1U << col));
89 		}
90 	}
91 
92 	input_sync(input);
93 
94 	writel(0x3, keypad->reg_base + KEYPAD_INT);
95 
96 	return IRQ_HANDLED;
97 }
98 
99 static int nspire_keypad_chip_init(struct nspire_keypad *keypad)
100 {
101 	unsigned long val = 0, cycles_per_us, delay_cycles, row_delay_cycles;
102 
103 	cycles_per_us = (clk_get_rate(keypad->clk) / 1000000);
104 	if (cycles_per_us == 0)
105 		cycles_per_us = 1;
106 
107 	delay_cycles = cycles_per_us * keypad->scan_interval;
108 	WARN_ON(delay_cycles >= (1 << 16)); /* Overflow */
109 	delay_cycles &= 0xffff;
110 
111 	row_delay_cycles = cycles_per_us * keypad->row_delay;
112 	WARN_ON(row_delay_cycles >= (1 << 14)); /* Overflow */
113 	row_delay_cycles &= 0x3fff;
114 
115 	val |= 3 << 0; /* Set scan mode to 3 (continuous scan) */
116 	val |= row_delay_cycles << 2; /* Delay between scanning each row */
117 	val |= delay_cycles << 16; /* Delay between scans */
118 	writel(val, keypad->reg_base + KEYPAD_SCAN_MODE);
119 
120 	val = (KEYPAD_BITMASK_ROWS & 0xff) | (KEYPAD_BITMASK_COLS & 0xff)<<8;
121 	writel(val, keypad->reg_base + KEYPAD_CNTL);
122 
123 	/* Enable interrupts */
124 	keypad->int_mask = 1 << 1;
125 	writel(keypad->int_mask, keypad->reg_base + KEYPAD_INTMSK);
126 
127 	/* Disable GPIO interrupts to prevent hanging on touchpad */
128 	/* Possibly used to detect touchpad events */
129 	writel(0, keypad->reg_base + KEYPAD_UNKNOWN_INT);
130 	/* Acknowledge existing interrupts */
131 	writel(~0, keypad->reg_base + KEYPAD_UNKNOWN_INT_STS);
132 
133 	return 0;
134 }
135 
136 static int nspire_keypad_open(struct input_dev *input)
137 {
138 	struct nspire_keypad *keypad = input_get_drvdata(input);
139 	int error;
140 
141 	error = clk_prepare_enable(keypad->clk);
142 	if (error)
143 		return error;
144 
145 	error = nspire_keypad_chip_init(keypad);
146 	if (error)
147 		return error;
148 
149 	return 0;
150 }
151 
152 static void nspire_keypad_close(struct input_dev *input)
153 {
154 	struct nspire_keypad *keypad = input_get_drvdata(input);
155 
156 	clk_disable_unprepare(keypad->clk);
157 }
158 
159 static int nspire_keypad_probe(struct platform_device *pdev)
160 {
161 	const struct device_node *of_node = pdev->dev.of_node;
162 	struct nspire_keypad *keypad;
163 	struct input_dev *input;
164 	struct resource *res;
165 	int irq;
166 	int error;
167 
168 	irq = platform_get_irq(pdev, 0);
169 	if (irq < 0) {
170 		dev_err(&pdev->dev, "failed to get keypad irq\n");
171 		return -EINVAL;
172 	}
173 
174 	keypad = devm_kzalloc(&pdev->dev, sizeof(struct nspire_keypad),
175 			      GFP_KERNEL);
176 	if (!keypad) {
177 		dev_err(&pdev->dev, "failed to allocate keypad memory\n");
178 		return -ENOMEM;
179 	}
180 
181 	keypad->row_shift = get_count_order(KEYPAD_BITMASK_COLS);
182 
183 	error = of_property_read_u32(of_node, "scan-interval",
184 				     &keypad->scan_interval);
185 	if (error) {
186 		dev_err(&pdev->dev, "failed to get scan-interval\n");
187 		return error;
188 	}
189 
190 	error = of_property_read_u32(of_node, "row-delay",
191 				     &keypad->row_delay);
192 	if (error) {
193 		dev_err(&pdev->dev, "failed to get row-delay\n");
194 		return error;
195 	}
196 
197 	keypad->active_low = of_property_read_bool(of_node, "active-low");
198 
199 	keypad->clk = devm_clk_get(&pdev->dev, NULL);
200 	if (IS_ERR(keypad->clk)) {
201 		dev_err(&pdev->dev, "unable to get clock\n");
202 		return PTR_ERR(keypad->clk);
203 	}
204 
205 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
206 	keypad->reg_base = devm_ioremap_resource(&pdev->dev, res);
207 	if (IS_ERR(keypad->reg_base))
208 		return PTR_ERR(keypad->reg_base);
209 
210 	keypad->input = input = devm_input_allocate_device(&pdev->dev);
211 	if (!input) {
212 		dev_err(&pdev->dev, "failed to allocate input device\n");
213 		return -ENOMEM;
214 	}
215 
216 	input_set_drvdata(input, keypad);
217 
218 	input->id.bustype = BUS_HOST;
219 	input->name = "nspire-keypad";
220 	input->open = nspire_keypad_open;
221 	input->close = nspire_keypad_close;
222 
223 	__set_bit(EV_KEY, input->evbit);
224 	__set_bit(EV_REP, input->evbit);
225 	input_set_capability(input, EV_MSC, MSC_SCAN);
226 
227 	error = matrix_keypad_build_keymap(NULL, NULL,
228 					   KEYPAD_BITMASK_ROWS,
229 					   KEYPAD_BITMASK_COLS,
230 					   NULL, input);
231 	if (error) {
232 		dev_err(&pdev->dev, "building keymap failed\n");
233 		return error;
234 	}
235 
236 	error = devm_request_irq(&pdev->dev, irq, nspire_keypad_irq, 0,
237 				 "nspire_keypad", keypad);
238 	if (error) {
239 		dev_err(&pdev->dev, "allocate irq %d failed\n", irq);
240 		return error;
241 	}
242 
243 	error = input_register_device(input);
244 	if (error) {
245 		dev_err(&pdev->dev,
246 			"unable to register input device: %d\n", error);
247 		return error;
248 	}
249 
250 	platform_set_drvdata(pdev, keypad);
251 
252 	dev_dbg(&pdev->dev,
253 		"TI-NSPIRE keypad at %pR (scan_interval=%uus, row_delay=%uus%s)\n",
254 		res, keypad->row_delay, keypad->scan_interval,
255 		keypad->active_low ? ", active_low" : "");
256 
257 	return 0;
258 }
259 
260 static const struct of_device_id nspire_keypad_dt_match[] = {
261 	{ .compatible = "ti,nspire-keypad" },
262 	{ },
263 };
264 MODULE_DEVICE_TABLE(of, nspire_keypad_dt_match);
265 
266 static struct platform_driver nspire_keypad_driver = {
267 	.driver = {
268 		.name = "nspire-keypad",
269 		.owner = THIS_MODULE,
270 		.of_match_table = of_match_ptr(nspire_keypad_dt_match),
271 	},
272 	.probe = nspire_keypad_probe,
273 };
274 
275 module_platform_driver(nspire_keypad_driver);
276 
277 MODULE_LICENSE("GPL");
278 MODULE_DESCRIPTION("TI-NSPIRE Keypad Driver");
279