Input: add TI-Nspire keypad support

This is a driver for the keypads found on the TI-Nspire series calculators.

Signed-off-by: Daniel Tang <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/ti,nspire-keypad.txt

···
+TI-NSPIRE Keypad
+
+Required properties:
+- compatible: Compatible property value should be "ti,nspire-keypad".
+
+- reg: Physical base address of the peripheral and length of memory mapped
+  region.
+
+- interrupts: The interrupt number for the peripheral.
+
+- scan-interval: How often to scan in us. Based on a APB speed of 33MHz, the
+	maximum and minimum delay time is ~2000us and ~500us respectively
+
+- row-delay: How long to wait before scanning each row.
+
+- clocks: The clock this peripheral is attached to.
+
+- linux,keymap: The keymap to use
+	(see Documentation/devicetree/bindings/input/matrix-keymap.txt)
+
+Optional properties:
+- active-low: Specify that the keypad is active low (i.e. logical low signifies
+	a key press).
+
+Example:
+
+input {
+	compatible = "ti,nspire-keypad";
+	reg = <0x900E0000 0x1000>;
+	interrupts = <16>;
+
+	scan-interval = <1000>;
+	row-delay = <200>;
+
+	clocks = <&apb_pclk>;
+
+	linux,keymap = <
+	0x0000001c	0x0001001c	0x00040039
+	0x0005002c	0x00060015	0x0007000b
+	0x0008000f	0x0100002d	0x01010011
+	0x0102002f	0x01030004	0x01040016
+	0x01050014	0x0106001f	0x01070002
+	0x010a006a	0x02000013	0x02010010
+	0x02020019	0x02030007	0x02040018
+	0x02050031	0x02060032	0x02070005
+	0x02080028	0x0209006c	0x03000026
+	0x03010025	0x03020024	0x0303000a
+	0x03040017	0x03050023	0x03060022
+	0x03070008	0x03080035	0x03090069
+	0x04000021	0x04010012	0x04020020
+	0x0404002e	0x04050030	0x0406001e
+	0x0407000d	0x04080037	0x04090067
+	0x05010038	0x0502000c	0x0503001b
+	0x05040034	0x0505001a	0x05060006
+	0x05080027	0x0509000e	0x050a006f
+	0x0600002b	0x0602004e	0x06030068
+	0x06040003	0x0605006d	0x06060009
+	0x06070001	0x0609000f	0x0708002a
+	0x0709001d	0x070a0033	>;
+};

drivers/input/keyboard/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called nmk-ske-keypad.
 
+config KEYBOARD_NSPIRE
+	tristate "TI-NSPIRE built-in keyboard"
+	depends on ARCH_NSPIRE && OF
+	select INPUT_MATRIXKMAP
+	help
+	  Say Y here if you want to use the built-in keypad on TI-NSPIRE.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called nspire-keypad.
+
 config KEYBOARD_TEGRA
 	tristate "NVIDIA Tegra internal matrix keyboard controller support"
 	depends on ARCH_TEGRA && OF

drivers/input/keyboard/Makefile

···
 obj-$(CONFIG_KEYBOARD_MPR121)		+= mpr121_touchkey.o
 obj-$(CONFIG_KEYBOARD_NEWTON)		+= newtonkbd.o
 obj-$(CONFIG_KEYBOARD_NOMADIK)		+= nomadik-ske-keypad.o
+obj-$(CONFIG_KEYBOARD_NSPIRE)		+= nspire-keypad.o
 obj-$(CONFIG_KEYBOARD_OMAP)		+= omap-keypad.o
 obj-$(CONFIG_KEYBOARD_OMAP4)		+= omap4-keypad.o
 obj-$(CONFIG_KEYBOARD_OPENCORES)	+= opencores-kbd.o

drivers/input/keyboard/nspire-keypad.c

···
+/*
+ *  Copyright (C) 2013 Daniel Tang <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/input/matrix_keypad.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+#define KEYPAD_SCAN_MODE	0x00
+#define KEYPAD_CNTL		0x04
+#define KEYPAD_INT		0x08
+#define KEYPAD_INTMSK		0x0C
+
+#define KEYPAD_DATA		0x10
+#define KEYPAD_GPIO		0x30
+
+#define KEYPAD_UNKNOWN_INT	0x40
+#define KEYPAD_UNKNOWN_INT_STS	0x44
+
+#define KEYPAD_BITMASK_COLS	11
+#define KEYPAD_BITMASK_ROWS	8
+
+struct nspire_keypad {
+	void __iomem *reg_base;
+	u32 int_mask;
+
+	struct input_dev *input;
+	struct clk *clk;
+
+	struct matrix_keymap_data *keymap;
+	int row_shift;
+
+	/* Maximum delay estimated assuming 33MHz APB */
+	u32 scan_interval;	/* In microseconds (~2000us max) */
+	u32 row_delay;		/* In microseconds (~500us max) */
+
+	u16 state[KEYPAD_BITMASK_ROWS];
+
+	bool active_low;
+};
+
+static irqreturn_t nspire_keypad_irq(int irq, void *dev_id)
+{
+	struct nspire_keypad *keypad = dev_id;
+	struct input_dev *input = keypad->input;
+	unsigned short *keymap = input->keycode;
+	unsigned int code;
+	int row, col;
+	u32 int_sts;
+	u16 state[8];
+	u16 bits, changed;
+
+	int_sts = readl(keypad->reg_base + KEYPAD_INT) & keypad->int_mask;
+	if (!int_sts)
+		return IRQ_NONE;
+
+	memcpy_fromio(state, keypad->reg_base + KEYPAD_DATA, sizeof(state));
+
+	for (row = 0; row < KEYPAD_BITMASK_ROWS; row++) {
+		bits = state[row];
+		if (keypad->active_low)
+			bits = ~bits;
+
+		changed = bits ^ keypad->state[row];
+		if (!changed)
+			continue;
+
+		keypad->state[row] = bits;
+
+		for (col = 0; col < KEYPAD_BITMASK_COLS; col++) {
+			if (!(changed & (1U << col)))
+				continue;
+
+			code = MATRIX_SCAN_CODE(row, col, keypad->row_shift);
+			input_event(input, EV_MSC, MSC_SCAN, code);
+			input_report_key(input, keymap[code],
+					 bits & (1U << col));
+		}
+	}
+
+	input_sync(input);
+
+	writel(0x3, keypad->reg_base + KEYPAD_INT);
+
+	return IRQ_HANDLED;
+}
+
+static int nspire_keypad_chip_init(struct nspire_keypad *keypad)
+{
+	unsigned long val = 0, cycles_per_us, delay_cycles, row_delay_cycles;
+
+	cycles_per_us = (clk_get_rate(keypad->clk) / 1000000);
+	if (cycles_per_us == 0)
+		cycles_per_us = 1;
+
+	delay_cycles = cycles_per_us * keypad->scan_interval;
+	WARN_ON(delay_cycles >= (1 << 16)); /* Overflow */
+	delay_cycles &= 0xffff;
+
+	row_delay_cycles = cycles_per_us * keypad->row_delay;
+	WARN_ON(row_delay_cycles >= (1 << 14)); /* Overflow */
+	row_delay_cycles &= 0x3fff;
+
+	val |= 3 << 0; /* Set scan mode to 3 (continuous scan) */
+	val |= row_delay_cycles << 2; /* Delay between scanning each row */
+	val |= delay_cycles << 16; /* Delay between scans */
+	writel(val, keypad->reg_base + KEYPAD_SCAN_MODE);
+
+	val = (KEYPAD_BITMASK_ROWS & 0xff) | (KEYPAD_BITMASK_COLS & 0xff)<<8;
+	writel(val, keypad->reg_base + KEYPAD_CNTL);
+
+	/* Enable interrupts */
+	keypad->int_mask = 1 << 1;
+	writel(keypad->int_mask, keypad->reg_base + 0xc);
+
+	/* Disable GPIO interrupts to prevent hanging on touchpad */
+	/* Possibly used to detect touchpad events */
+	writel(0, keypad->reg_base + KEYPAD_UNKNOWN_INT);
+	/* Acknowledge existing interrupts */
+	writel(~0, keypad->reg_base + KEYPAD_UNKNOWN_INT_STS);
+
+	return 0;
+}
+
+static int nspire_keypad_open(struct input_dev *input)
+{
+	struct nspire_keypad *keypad = input_get_drvdata(input);
+	int error;
+
+	error = clk_prepare_enable(keypad->clk);
+	if (error)
+		return error;
+
+	error = nspire_keypad_chip_init(keypad);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static void nspire_keypad_close(struct input_dev *input)
+{
+	struct nspire_keypad *keypad = input_get_drvdata(input);
+
+	clk_disable_unprepare(keypad->clk);
+}
+
+static int nspire_keypad_probe(struct platform_device *pdev)
+{
+	const struct device_node *of_node = pdev->dev.of_node;
+	struct nspire_keypad *keypad;
+	struct input_dev *input;
+	struct resource *res;
+	int irq;
+	int error;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "failed to get keypad irq\n");
+		return -EINVAL;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "missing platform resources\n");
+		return -EINVAL;
+	}
+
+	keypad = devm_kzalloc(&pdev->dev, sizeof(struct nspire_keypad),
+			      GFP_KERNEL);
+	if (!keypad) {
+		dev_err(&pdev->dev, "failed to allocate keypad memory\n");
+		return -ENOMEM;
+	}
+
+	keypad->row_shift = get_count_order(KEYPAD_BITMASK_COLS);
+
+	error = of_property_read_u32(of_node, "scan-interval",
+				     &keypad->scan_interval);
+	if (error) {
+		dev_err(&pdev->dev, "failed to get scan-interval\n");
+		return error;
+	}
+
+	error = of_property_read_u32(of_node, "row-delay",
+				     &keypad->row_delay);
+	if (error) {
+		dev_err(&pdev->dev, "failed to get row-delay\n");
+		return error;
+	}
+
+	keypad->active_low = of_property_read_bool(of_node, "active-low");
+
+	keypad->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(keypad->clk)) {
+		dev_err(&pdev->dev, "unable to get clock\n");
+		return PTR_ERR(keypad->clk);
+	}
+
+	keypad->reg_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(keypad->reg_base)) {
+		dev_err(&pdev->dev, "failed to remap I/O memory\n");
+		return PTR_ERR(keypad->reg_base);
+	}
+
+	keypad->input = input = devm_input_allocate_device(&pdev->dev);
+	if (!input) {
+		dev_err(&pdev->dev, "failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	input_set_drvdata(input, keypad);
+
+	input->id.bustype = BUS_HOST;
+	input->name = "nspire-keypad";
+	input->open = nspire_keypad_open;
+	input->close = nspire_keypad_close;
+
+	__set_bit(EV_KEY, input->evbit);
+	__set_bit(EV_REP, input->evbit);
+	input_set_capability(input, EV_MSC, MSC_SCAN);
+
+	error = matrix_keypad_build_keymap(NULL, NULL,
+					   KEYPAD_BITMASK_ROWS,
+					   KEYPAD_BITMASK_COLS,
+					   NULL, input);
+	if (error) {
+		dev_err(&pdev->dev, "building keymap failed\n");
+		return error;
+	}
+
+	error = devm_request_irq(&pdev->dev, irq, nspire_keypad_irq, 0,
+				 "nspire_keypad", keypad);
+	if (error) {
+		dev_err(&pdev->dev, "allocate irq %d failed\n", irq);
+		return error;
+	}
+
+	error = input_register_device(input);
+	if (error) {
+		dev_err(&pdev->dev,
+			"unable to register input device: %d\n", error);
+		return error;
+	}
+
+	platform_set_drvdata(pdev, keypad);
+
+	dev_dbg(&pdev->dev,
+		"TI-NSPIRE keypad at %pR (scan_interval=%uus, row_delay=%uus%s)\n",
+		res, keypad->row_delay, keypad->scan_interval,
+		keypad->active_low ? ", active_low" : "");
+
+	return 0;
+}
+
+static const struct of_device_id nspire_keypad_dt_match[] = {
+	{ .compatible = "ti,nspire-keypad" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, nspire_keypad_dt_match);
+
+static struct platform_driver nspire_keypad_driver = {
+	.driver = {
+		.name = "nspire-keypad",
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(nspire_keypad_dt_match),
+	},
+	.probe = nspire_keypad_probe,
+};
+
+module_platform_driver(nspire_keypad_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TI-NSPIRE Keypad Driver");