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da850-evm: add UI Expander pushbuttons

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This patch adds EV_KEYs for each of the 8 pushbuttons on the UI board via a
gpio-key device.

The expander is a tca6416; it controls the SEL_{A,B,C} lines which enable and
disable the peripherals found on the UI board in addition to the 8 pushbuttons
mentioned above. The reason the existing tca6416-keypad driver is not employed
is because there was no aparent way to keep the gpio lines used as
SEL_{A,B,C} registered while simultaneously registering the pushbuttons as a
tca6416-keypad instance.

Some experimentation with the polling interval was performed; we were searching
for the largest polling interval that did not affect the feel of the
responsiveness of the buttons. It is very subjective but 200ms seems to be a
good value that accepts firm pushes but rejects very light ones. The key values
assigned to the buttons were arbitrarily chosen to be F1-F8.

Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
Reviewed-by: Chris Cordahi <christophercordahi@nanometrics.ca>
CC: Govindarajan, Sriramakrishnan <srk@ti.com>
Reviewed-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
CC: Kevin Hilman <khilman@deeprootsystems.com>
CC: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
This commit is contained in:
Ben Gardiner 2010-12-09 16:51:04 -05:00 committed by Kevin Hilman
parent 22ca466847
commit 75929f5e2b
1 changed files with 95 additions and 0 deletions
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95
arch/arm/mach-davinci/board-da850-evm.c
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@ -17,8 +17,10 @@
#include <linux/i2c.h>
#include <linux/i2c/at24.h>
#include <linux/i2c/pca953x.h>
#include <linux/input.h>
#include <linux/mfd/tps6507x.h>
#include <linux/gpio.h>
#include <linux/gpio_keys.h>
#include <linux/platform_device.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
@ -272,6 +274,87 @@ static inline void da850_evm_setup_emac_rmii(int rmii_sel)
static inline void da850_evm_setup_emac_rmii(int rmii_sel) { }
#endif
#define DA850_KEYS_DEBOUNCE_MS 10
/*
* At 200ms polling interval it is possible to miss an
* event by tapping very lightly on the push button but most
* pushes do result in an event; longer intervals require the
* user to hold the button whereas shorter intervals require
* more CPU time for polling.
*/
#define DA850_GPIO_KEYS_POLL_MS 200
enum da850_evm_ui_exp_pins {
DA850_EVM_UI_EXP_SEL_C = 5,
DA850_EVM_UI_EXP_SEL_B,
DA850_EVM_UI_EXP_SEL_A,
DA850_EVM_UI_EXP_PB8,
DA850_EVM_UI_EXP_PB7,
DA850_EVM_UI_EXP_PB6,
DA850_EVM_UI_EXP_PB5,
DA850_EVM_UI_EXP_PB4,
DA850_EVM_UI_EXP_PB3,
DA850_EVM_UI_EXP_PB2,
DA850_EVM_UI_EXP_PB1,
};
static const char const *da850_evm_ui_exp[] = {
[DA850_EVM_UI_EXP_SEL_C] = "sel_c",
[DA850_EVM_UI_EXP_SEL_B] = "sel_b",
[DA850_EVM_UI_EXP_SEL_A] = "sel_a",
[DA850_EVM_UI_EXP_PB8] = "pb8",
[DA850_EVM_UI_EXP_PB7] = "pb7",
[DA850_EVM_UI_EXP_PB6] = "pb6",
[DA850_EVM_UI_EXP_PB5] = "pb5",
[DA850_EVM_UI_EXP_PB4] = "pb4",
[DA850_EVM_UI_EXP_PB3] = "pb3",
[DA850_EVM_UI_EXP_PB2] = "pb2",
[DA850_EVM_UI_EXP_PB1] = "pb1",
};
#define DA850_N_UI_PB 8
static struct gpio_keys_button da850_evm_ui_keys[] = {
[0 ... DA850_N_UI_PB - 1] = {
.type = EV_KEY,
.active_low = 1,
.wakeup = 0,
.debounce_interval = DA850_KEYS_DEBOUNCE_MS,
.code = -1, /* assigned at runtime */
.gpio = -1, /* assigned at runtime */
.desc = NULL, /* assigned at runtime */
},
};
static struct gpio_keys_platform_data da850_evm_ui_keys_pdata = {
.buttons = da850_evm_ui_keys,
.nbuttons = ARRAY_SIZE(da850_evm_ui_keys),
.poll_interval = DA850_GPIO_KEYS_POLL_MS,
};
static struct platform_device da850_evm_ui_keys_device = {
.name = "gpio-keys-polled",
.id = 0,
.dev = {
.platform_data = &da850_evm_ui_keys_pdata
},
};
static void da850_evm_ui_keys_init(unsigned gpio)
{
int i;
struct gpio_keys_button *button;
for (i = 0; i < DA850_N_UI_PB; i++) {
button = &da850_evm_ui_keys[i];
button->code = KEY_F8 - i;
button->desc = (char *)
da850_evm_ui_exp[DA850_EVM_UI_EXP_PB8 + i];
button->gpio = gpio + DA850_EVM_UI_EXP_PB8 + i;
}
}
static int da850_evm_ui_expander_setup(struct i2c_client *client, unsigned gpio,
unsigned ngpio, void *c)
{
@ -304,6 +387,13 @@ static int da850_evm_ui_expander_setup(struct i2c_client *client, unsigned gpio,
gpio_direction_output(sel_b, 1);
gpio_direction_output(sel_c, 1);
da850_evm_ui_keys_init(gpio);
ret = platform_device_register(&da850_evm_ui_keys_device);
if (ret) {
pr_warning("Could not register UI GPIO expander push-buttons");
goto exp_setup_keys_fail;
}
ui_card_detected = 1;
pr_info("DA850/OMAP-L138 EVM UI card detected\n");
@ -313,6 +403,8 @@ static int da850_evm_ui_expander_setup(struct i2c_client *client, unsigned gpio,
return 0;
exp_setup_keys_fail:
gpio_free(sel_c);
exp_setup_selc_fail:
gpio_free(sel_b);
exp_setup_selb_fail:
@ -324,6 +416,8 @@ exp_setup_sela_fail:
static int da850_evm_ui_expander_teardown(struct i2c_client *client,
unsigned gpio, unsigned ngpio, void *c)
{
platform_device_unregister(&da850_evm_ui_keys_device);
/* deselect all functionalities */
gpio_set_value_cansleep(gpio + 5, 1);
gpio_set_value_cansleep(gpio + 6, 1);
@ -340,6 +434,7 @@ static struct pca953x_platform_data da850_evm_ui_expander_info = {
.gpio_base = DAVINCI_N_GPIO,
.setup = da850_evm_ui_expander_setup,
.teardown = da850_evm_ui_expander_teardown,
.names = da850_evm_ui_exp,
};
static struct i2c_board_info __initdata da850_evm_i2c_devices[] = {