tegra: Add tegra keyboard driver

Add support for internal matrix keyboard controller for Nvidia Tegra
platforms. This driver uses the fdt decode function to obtain its key
codes.

Support for the Ctrl modifier is provided. The left and right ctrl keys are
dealt with in the same way.

This uses the new keyboard input library (drivers/input/input.c) to decode
keys and handle most of the common input logic. The new key matrix library
is also used to decode (row, column) key positions into key codes.

The intent is to make this driver purely about dealing with the hardware.

Key detection before the driver is loaded is supported. This key will be
picked up when the keyboard driver is initialized.

Modified by Bernie Thompson <bhthompson@chromium.org> and
Simon Glass <sjg@chromium.org> for device tree, input layer, key matrix
and various other things.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 375 insertions, 0 deletions

diff --git a/drivers/input/tegra-kbc.c b/drivers/input/tegra-kbc.c
new file mode 100644
index 0000000..f164791
--- /dev/null
+++ b/drivers/input/tegra-kbc.c
@@ -0,0 +1,375 @@
+/*
+ *  (C) Copyright 2011
+ *  NVIDIA Corporation <www.nvidia.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <fdtdec.h>
+#include <input.h>
+#include <key_matrix.h>
+#include <stdio_dev.h>
+#include <tegra-kbc.h>
+#include <asm/io.h>
+#include <asm/arch/clock.h>
+#include <asm/arch/funcmux.h>
+#include <asm/arch/timer.h>
+#include <linux/input.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+enum {
+	KBC_MAX_GPIO		= 24,
+	KBC_MAX_KPENT		= 8,	/* size of keypress entry queue */
+};
+
+#define KBC_FIFO_TH_CNT_SHIFT		14
+#define KBC_DEBOUNCE_CNT_SHIFT		4
+#define KBC_CONTROL_FIFO_CNT_INT_EN	(1 << 3)
+#define KBC_CONTROL_KBC_EN		(1 << 0)
+#define KBC_INT_FIFO_CNT_INT_STATUS	(1 << 2)
+#define KBC_KPENT_VALID			(1 << 7)
+#define KBC_ST_STATUS			(1 << 3)
+
+enum {
+	KBC_DEBOUNCE_COUNT	= 2,
+	KBC_REPEAT_RATE_MS	= 30,
+	KBC_REPEAT_DELAY_MS	= 240,
+	KBC_CLOCK_KHZ		= 32,	/* Keyboard uses a 32KHz clock */
+};
+
+/* keyboard controller config and state */
+static struct keyb {
+	struct input_config input;	/* The input layer */
+	struct key_matrix matrix;	/* The key matrix layer */
+
+	struct kbc_tegra *kbc;		/* tegra keyboard controller */
+	unsigned char inited;		/* 1 if keyboard has been inited */
+	unsigned char first_scan;	/* 1 if this is our first key scan */
+
+	/*
+	 * After init we must wait a short time before polling the keyboard.
+	 * This gives the tegra keyboard controller time to react after reset
+	 * and lets us grab keys pressed during reset.
+	 */
+	unsigned int init_dly_ms;	/* Delay before we can read keyboard */
+	unsigned int start_time_ms;	/* Time that we inited (in ms) */
+	unsigned int last_poll_ms;	/* Time we should last polled */
+	unsigned int next_repeat_ms;	/* Next time we repeat a key */
+} config;
+
+/**
+ * reads the keyboard fifo for current keypresses
+ *
+ * @param config	Keyboard config
+ * @param fifo		Place to put fifo results
+ * @param max_keycodes	Maximum number of key codes to put in the fifo
+ * @return number of items put into fifo
+ */
+static int tegra_kbc_find_keys(struct keyb *config, int *fifo,
+			       int max_keycodes)
+{
+	struct key_matrix_key keys[KBC_MAX_KPENT], *key;
+	u32 kp_ent = 0;
+	int i;
+
+	for (key = keys, i = 0; i < KBC_MAX_KPENT; i++, key++) {
+		/* Get next word */
+		if (!(i & 3))
+			kp_ent = readl(&config->kbc->kp_ent[i / 4]);
+
+		key->valid = (kp_ent & KBC_KPENT_VALID) != 0;
+		key->row = (kp_ent >> 3) & 0xf;
+		key->col = kp_ent & 0x7;
+
+		/* Shift to get next entry */
+		kp_ent >>= 8;
+	}
+	return key_matrix_decode(&config->matrix, keys, KBC_MAX_KPENT, fifo,
+				 max_keycodes);
+}
+
+/**
+ * Process all the keypress sequences in fifo and send key codes
+ *
+ * The fifo contains zero or more keypress sets. Each set
+ * consists of from 1-8 keycodes, representing the keycodes which
+ * were simultaneously pressed during that scan.
+ *
+ * This function works through each set and generates ASCII characters
+ * for each. Not that one set may produce more than one ASCII characters -
+ * for example holding down 'd' and 'f' at the same time will generate
+ * two ASCII characters.
+ *
+ * Note: if fifo_cnt is 0, we will tell the input layer that no keys are
+ * pressed.
+ *
+ * @param config	Keyboard config
+ * @param fifo_cnt	Number of entries in the keyboard fifo
+ */
+static void process_fifo(struct keyb *config, int fifo_cnt)
+{
+	int fifo[KBC_MAX_KPENT];
+	int cnt = 0;
+
+	/* Always call input_send_keycodes() at least once */
+	do {
+		if (fifo_cnt)
+			cnt = tegra_kbc_find_keys(config, fifo, KBC_MAX_KPENT);
+
+		input_send_keycodes(&config->input, fifo, cnt);
+	} while (--fifo_cnt > 0);
+}
+
+/**
+ * Check the keyboard controller and emit ASCII characters for any keys that
+ * are pressed.
+ *
+ * @param config	Keyboard config
+ */
+static void check_for_keys(struct keyb *config)
+{
+	int fifo_cnt;
+
+	if (!config->first_scan &&
+			get_timer(config->last_poll_ms) < KBC_REPEAT_RATE_MS)
+		return;
+	config->last_poll_ms = get_timer(0);
+	config->first_scan = 0;
+
+	/*
+	 * Once we get here we know the keyboard has been scanned. So if there
+	 * scan waiting for us, we know that nothing is held down.
+	 */
+	fifo_cnt = (readl(&config->kbc->interrupt) >> 4) & 0xf;
+	process_fifo(config, fifo_cnt);
+}
+
+/**
+ * In order to detect keys pressed on boot, wait for the hardware to
+ * complete scanning the keys. This includes time to transition from
+ * Wkup mode to Continous polling mode and the repoll time. We can
+ * deduct the time that's already elapsed.
+ *
+ * @param config	Keyboard config
+ */
+static void kbd_wait_for_fifo_init(struct keyb *config)
+{
+	if (!config->inited) {
+		unsigned long elapsed_time;
+		long delay_ms;
+
+		elapsed_time = get_timer(config->start_time_ms);
+		delay_ms = config->init_dly_ms - elapsed_time;
+		if (delay_ms > 0) {
+			udelay(delay_ms * 1000);
+			debug("%s: delay %ldms\n", __func__, delay_ms);
+		}
+
+		config->inited = 1;
+	}
+}
+
+/**
+ * Check the tegra keyboard, and send any keys that are pressed.
+ *
+ * This is called by input_tstc() and input_getc() when they need more
+ * characters
+ *
+ * @param input		Input configuration
+ * @return 1, to indicate that we have something to look at
+ */
+int tegra_kbc_check(struct input_config *input)
+{
+	kbd_wait_for_fifo_init(&config);
+	check_for_keys(&config);
+
+	return 1;
+}
+
+/**
+ * Test if keys are available to be read
+ *
+ * @return 0 if no keys available, 1 if keys are available
+ */
+static int kbd_tstc(void)
+{
+	/* Just get input to do this for us */
+	return input_tstc(&config.input);
+}
+
+/**
+ * Read a key
+ *
+ * TODO: U-Boot wants 0 for no key, but Ctrl-@ is a valid key...
+ *
+ * @return ASCII key code, or 0 if no key, or -1 if error
+ */
+static int kbd_getc(void)
+{
+	/* Just get input to do this for us */
+	return input_getc(&config.input);
+}
+
+/* configures keyboard GPIO registers to use the rows and columns */
+static void config_kbc_gpio(struct kbc_tegra *kbc)
+{
+	int i;
+
+	for (i = 0; i < KBC_MAX_GPIO; i++) {
+		u32 row_cfg, col_cfg;
+		u32 r_shift = 5 * (i % 6);
+		u32 c_shift = 4 * (i % 8);
+		u32 r_mask = 0x1f << r_shift;
+		u32 c_mask = 0xf << c_shift;
+		u32 r_offs = i / 6;
+		u32 c_offs = i / 8;
+
+		row_cfg = readl(&kbc->row_cfg[r_offs]);
+		col_cfg = readl(&kbc->col_cfg[c_offs]);
+
+		row_cfg &= ~r_mask;
+		col_cfg &= ~c_mask;
+
+		if (i < config.matrix.num_rows) {
+			row_cfg |= ((i << 1) | 1) << r_shift;
+		} else {
+			col_cfg |= (((i - config.matrix.num_rows) << 1) | 1)
+					<< c_shift;
+		}
+
+		writel(row_cfg, &kbc->row_cfg[r_offs]);
+		writel(col_cfg, &kbc->col_cfg[c_offs]);
+	}
+}
+
+/**
+ * Start up the keyboard device
+ */
+static void tegra_kbc_open(void)
+{
+	struct kbc_tegra *kbc = config.kbc;
+	unsigned int scan_period;
+	u32 val;
+
+	/*
+	 * We will scan at twice the keyboard repeat rate, so that there is
+	 * always a scan ready when we check it in check_for_keys().
+	 */
+	scan_period = KBC_REPEAT_RATE_MS / 2;
+	writel(scan_period * KBC_CLOCK_KHZ, &kbc->rpt_dly);
+	writel(scan_period * KBC_CLOCK_KHZ, &kbc->init_dly);
+	/*
+	 * Before reading from the keyboard we must wait for the init_dly
+	 * plus the rpt_delay, plus 2ms for the row scan time.
+	 */
+	config.init_dly_ms = scan_period * 2 + 2;
+
+	val = KBC_DEBOUNCE_COUNT << KBC_DEBOUNCE_CNT_SHIFT;
+	val |= 1 << KBC_FIFO_TH_CNT_SHIFT;	/* fifo interrupt threshold */
+	val |= KBC_CONTROL_KBC_EN;		/* enable */
+	writel(val, &kbc->control);
+
+	config.start_time_ms = get_timer(0);
+	config.last_poll_ms = config.next_repeat_ms = get_timer(0);
+	config.first_scan = 1;
+}
+
+/**
+ * Set up the tegra keyboard. This is called by the stdio device handler
+ *
+ * We want to do this init when the keyboard is actually used rather than
+ * at start-up, since keyboard input may not currently be selected.
+ *
+ * Once the keyboard starts there will be a period during which we must
+ * wait for the keyboard to init. We do this only when a key is first
+ * read - see kbd_wait_for_fifo_init().
+ *
+ * @return 0 if ok, -ve on error
+ */
+static int init_tegra_keyboard(void)
+{
+#ifdef CONFIG_OF_CONTROL
+	int	node;
+
+	node = fdtdec_next_compatible(gd->fdt_blob, 0,
+					  COMPAT_NVIDIA_TEGRA20_KBC);
+	if (node < 0) {
+		debug("%s: cannot locate keyboard node\n", __func__);
+		return node;
+	}
+	config.kbc = (struct kbc_tegra *)fdtdec_get_addr(gd->fdt_blob,
+		       node, "reg");
+	if ((fdt_addr_t)config.kbc == FDT_ADDR_T_NONE) {
+		debug("%s: No keyboard register found\n", __func__);
+		return -1;
+	}
+
+	/* Decode the keyboard matrix information (16 rows, 8 columns) */
+	if (key_matrix_init(&config.matrix, 16, 8)) {
+		debug("%s: Could not init key matrix\n", __func__);
+		return -1;
+	}
+	if (key_matrix_decode_fdt(&config.matrix, gd->fdt_blob, node)) {
+		debug("%s: Could not decode key matrix from fdt\n", __func__);
+		return -1;
+	}
+	if (config.matrix.fn_keycode) {
+		if (input_add_table(&config.input, KEY_FN, -1,
+				    config.matrix.fn_keycode,
+				    config.matrix.key_count))
+			return -1;
+	}
+#else
+#error "Tegra keyboard driver requires FDT definitions"
+#endif
+
+	/* Set up pin mux and enable the clock */
+	funcmux_select(PERIPH_ID_KBC, FUNCMUX_DEFAULT);
+	clock_enable(PERIPH_ID_KBC);
+	config_kbc_gpio(config.kbc);
+
+	tegra_kbc_open();
+	debug("%s: Tegra keyboard ready\n", __func__);
+
+	return 0;
+}
+
+int drv_keyboard_init(void)
+{
+	struct stdio_dev dev;
+
+	if (input_init(&config.input, 0, KBC_REPEAT_DELAY_MS,
+			KBC_REPEAT_RATE_MS)) {
+		debug("%s: Cannot set up input\n", __func__);
+		return -1;
+	}
+	config.input.read_keys = tegra_kbc_check;
+
+	memset(&dev, '\0', sizeof(dev));
+	strcpy(dev.name, "tegra-kbc");
+	dev.flags = DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;
+	dev.getc = kbd_getc;
+	dev.tstc = kbd_tstc;
+	dev.start = init_tegra_keyboard;
+
+	/* Register the device. init_tegra_keyboard() will be called soon */
+	return input_stdio_register(&dev);
+}