Input: tegra-kbc - add ghost key filter
Add ghost key filtering support for the Nvidia Tegra matrix keyboard. Signed-off-by: Rakesh Iyer <riyer@nvidia.com> Reviewed-by: Henrik Rydberg <rydberg@euromail.se> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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@ -58,5 +58,6 @@ struct tegra_kbc_platform_data {
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bool wakeup;
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bool use_fn_map;
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bool use_ghost_filter;
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};
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#endif
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@ -72,6 +72,7 @@ struct tegra_kbc {
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unsigned int repoll_dly;
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unsigned long cp_dly_jiffies;
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bool use_fn_map;
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bool use_ghost_filter;
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const struct tegra_kbc_platform_data *pdata;
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unsigned short keycode[KBC_MAX_KEY * 2];
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unsigned short current_keys[KBC_MAX_KPENT];
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@ -260,6 +261,8 @@ static void tegra_kbc_report_keys(struct tegra_kbc *kbc)
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unsigned int num_down = 0;
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unsigned long flags;
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bool fn_keypress = false;
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bool key_in_same_row = false;
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bool key_in_same_col = false;
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spin_lock_irqsave(&kbc->lock, flags);
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for (i = 0; i < KBC_MAX_KPENT; i++) {
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@ -284,6 +287,34 @@ static void tegra_kbc_report_keys(struct tegra_kbc *kbc)
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val >>= 8;
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}
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/*
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* Matrix keyboard designs are prone to keyboard ghosting.
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* Ghosting occurs if there are 3 keys such that -
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* any 2 of the 3 keys share a row, and any 2 of them share a column.
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* If so ignore the key presses for this iteration.
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*/
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if ((kbc->use_ghost_filter) && (num_down >= 3)) {
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for (i = 0; i < num_down; i++) {
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unsigned int j;
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u8 curr_col = scancodes[i] & 0x07;
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u8 curr_row = scancodes[i] >> KBC_ROW_SHIFT;
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/*
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* Find 2 keys such that one key is in the same row
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* and the other is in the same column as the i-th key.
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*/
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for (j = i + 1; j < num_down; j++) {
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u8 col = scancodes[j] & 0x07;
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u8 row = scancodes[j] >> KBC_ROW_SHIFT;
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if (col == curr_col)
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key_in_same_col = true;
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if (row == curr_row)
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key_in_same_row = true;
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}
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}
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}
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/*
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* If the platform uses Fn keymaps, translate keys on a Fn keypress.
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* Function keycodes are KBC_MAX_KEY apart from the plain keycodes.
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@ -297,6 +328,10 @@ static void tegra_kbc_report_keys(struct tegra_kbc *kbc)
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spin_unlock_irqrestore(&kbc->lock, flags);
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/* Ignore the key presses for this iteration? */
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if (key_in_same_col && key_in_same_row)
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return;
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tegra_kbc_report_released_keys(kbc->idev,
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kbc->current_keys, kbc->num_pressed_keys,
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keycodes, num_down);
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@ -652,6 +687,7 @@ static int __devinit tegra_kbc_probe(struct platform_device *pdev)
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input_dev->keycodemax *= 2;
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kbc->use_fn_map = pdata->use_fn_map;
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kbc->use_ghost_filter = pdata->use_ghost_filter;
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keymap_data = pdata->keymap_data ?: &tegra_kbc_default_keymap_data;
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matrix_keypad_build_keymap(keymap_data, KBC_ROW_SHIFT,
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input_dev->keycode, input_dev->keybit);
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