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Subject[PATCH v3 2/4] da850-evm: add UI Expander pushbuttons
Date
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>

---
Changes since v2:
* rebased to 083eae3e28643e0eefc5243719f8b1572cf98299 of
git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-davinci.git
* remove the "TODO : populate at runtime using" in this patch instead of 4/4
(Nori, Sekhar)
* integrated the static array initialization patch of Sekhar Nori
* use static array initialization ranges
* rename DA850_PB_POLL_MS to DA850_GPIO_KEYS_POLL_MS
* use shorter names prefixed with da850_evm

Changes since v1:
* set INPUT_POLLDEV default for DA850_EVM machine, but don't select it
unconditionally
* adding note to description about why tca6416-keypad was not used
* adding Govindarajan, Sriramakrishnan, the author of the tca6416-keypad
driver

---
arch/arm/mach-davinci/Kconfig | 3 +
arch/arm/mach-davinci/board-da850-evm.c | 98 ++++++++++++++++++++++++++++++-
2 files changed, 100 insertions(+), 1 deletions(-)
diff --git a/arch/arm/mach-davinci/Kconfig b/arch/arm/mach-davinci/Kconfig
index 84066e8..1fbf73f 100644
--- a/arch/arm/mach-davinci/Kconfig
+++ b/arch/arm/mach-davinci/Kconfig
@@ -180,6 +180,9 @@ endchoice
config GPIO_PCA953X
default MACH_DAVINCI_DA850_EVM

+config INPUT_POLLDEV
+ default MACH_DAVINCI_DA850_EVM
+
config MACH_TNETV107X
bool "TI TNETV107X Reference Platform"
default ARCH_DAVINCI_TNETV107X
diff --git a/arch/arm/mach-davinci/board-da850-evm.c b/arch/arm/mach-davinci/board-da850-evm.c
index f89b0b7..b0763f7 100644
--- a/arch/arm/mach-davinci/board-da850-evm.c
+++ b/arch/arm/mach-davinci/board-da850-evm.c
@@ -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 +274,88 @@ 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),
+ .rep = 0, /* disable auto-repeat */
+ .poll_interval = DA850_GPIO_KEYS_POLL_MS,
+};
+
+static struct platform_device da850_evm_ui_keys_device = {
+ .name = "gpio-keys",
+ .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)
{
@@ -304,15 +388,24 @@ 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"
+ " device\n");
+ goto exp_setup_keys_fail;
+ }
+
ui_card_detected = 1;
pr_info("DA850/OMAP-L138 EVM UI card detected\n");

da850_evm_setup_nor_nand();
-
da850_evm_setup_emac_rmii(sel_a);

return 0;

+exp_setup_keys_fail:
+ gpio_free(sel_c);
exp_setup_selc_fail:
gpio_free(sel_b);
exp_setup_selb_fail:
@@ -324,6 +417,8 @@ 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 +435,7 @@ 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[] = {
--
1.7.0.4


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