Input: spear_keyboard - reconfigure operating frequency on suspend

On some platform it may happen that the input clock to keyboard may
change during suspend, thus impacting its wakeup capability.

There is no means for keyboard driver to know this frequency before
hand. Hence introduce a platform data 'suspended_rate' which indicates
the frequency during suspend at which keyboard operates.

Accordingly reprogram keyboard while going into suspend and restore
original configuration at the time of resume.
Signed-off-by: Shiraz Hashim <shiraz.hashim@st.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

arch/arm/plat-spear/include/plat/keyboard.h

@@ -149,6 +149,7 @@ int _name[] = { \
  * keymap: pointer to keymap data (table and size)
  * rep: enables key autorepeat
  * mode: choose keyboard support(9x9, 6x6, 2x2)
+ * suspended_rate: rate at which keyboard would operate in suspended mode
  *
  * This structure is supposed to be used by platform code to supply
  * keymaps to drivers that implement keyboards.
@@ -157,6 +158,7 @@ struct kbd_platform_data {
 	const struct matrix_keymap_data *keymap;
 	bool rep;
 	unsigned int mode;
+	unsigned int suspended_rate;
 };
 
 #endif /* __PLAT_KEYBOARD_H */

drivers/input/keyboard/spear-keyboard.c

@@ -63,6 +63,8 @@ struct spear_kbd {
 	unsigned short last_key;
 	unsigned short keycodes[NUM_ROWS * NUM_COLS];
 	bool rep;
+	unsigned int suspended_rate;
+	u32 mode_ctl_reg;
 };
 
 static irqreturn_t spear_kbd_interrupt(int irq, void *dev_id)
@@ -149,7 +151,7 @@ static int __devinit spear_kbd_parse_dt(struct platform_device *pdev,
 {
 	struct device_node *np = pdev->dev.of_node;
 	int error;
-	u32 val;
+	u32 val, suspended_rate;
 
 	if (!np) {
 		dev_err(&pdev->dev, "Missing DT data\n");
@@ -159,6 +161,9 @@ static int __devinit spear_kbd_parse_dt(struct platform_device *pdev,
 	if (of_property_read_bool(np, "autorepeat"))
 		kbd->rep = true;
 
+	if (of_property_read_u32(np, "suspended_rate", &suspended_rate))
+		kbd->suspended_rate = suspended_rate;
+
 	error = of_property_read_u32(np, "st,mode", &val);
 	if (error) {
 		dev_err(&pdev->dev, "DT: Invalid or missing mode\n");
@@ -216,6 +221,7 @@ static int __devinit spear_kbd_probe(struct platform_device *pdev)
 	} else {
 		kbd->mode = pdata->mode;
 		kbd->rep = pdata->rep;
+		kbd->suspended_rate = pdata->suspended_rate;
 	}
 
 	kbd->res = request_mem_region(res->start, resource_size(res),
@@ -317,16 +323,48 @@ static int spear_kbd_suspend(struct device *dev)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct spear_kbd *kbd = platform_get_drvdata(pdev);
 	struct input_dev *input_dev = kbd->input;
+	unsigned int rate = 0, mode_ctl_reg, val;
 
 	mutex_lock(&input_dev->mutex);
 
+	/* explicitly enable clock as we may program device */
+	clk_enable(kbd->clk);
+
+	mode_ctl_reg = readl_relaxed(kbd->io_base + MODE_CTL_REG);
+
 	if (device_may_wakeup(&pdev->dev)) {
 		enable_irq_wake(kbd->irq);
+
+		/*
+		 * reprogram the keyboard operating frequency as on some
+		 * platform it may change during system suspended
+		 */
+		if (kbd->suspended_rate)
+			rate = kbd->suspended_rate / 1000000 - 1;
+		else
+			rate = clk_get_rate(kbd->clk) / 1000000 - 1;
+
+		val = mode_ctl_reg &
+			~(MODE_CTL_PCLK_FREQ_MSK << MODE_CTL_PCLK_FREQ_SHIFT);
+		val |= (rate & MODE_CTL_PCLK_FREQ_MSK)
+			<< MODE_CTL_PCLK_FREQ_SHIFT;
+		writel_relaxed(val, kbd->io_base + MODE_CTL_REG);
+
 	} else {
-		if (input_dev->users)
+		if (input_dev->users) {
+			writel_relaxed(mode_ctl_reg & ~MODE_CTL_START_SCAN,
+					kbd->io_base + MODE_CTL_REG);
 			clk_disable(kbd->clk);
+		}
 	}
 
+	/* store current configuration */
+	if (input_dev->users)
+		kbd->mode_ctl_reg = mode_ctl_reg;
+
+	/* restore previous clk state */
+	clk_disable(kbd->clk);
+
 	mutex_unlock(&input_dev->mutex);
 
 	return 0;
@@ -347,6 +385,10 @@ static int spear_kbd_resume(struct device *dev)
 			clk_enable(kbd->clk);
 	}
 
+	/* restore current configuration */
+	if (input_dev->users)
+		writel_relaxed(kbd->mode_ctl_reg, kbd->io_base + MODE_CTL_REG);
+
 	mutex_unlock(&input_dev->mutex);
 
 	return 0;