i2c: at91: add support for analog filtering

Add support for analog filtering for i2c lines.
The sama5d2 and sam9x60 support this feature.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>

Author: ehristev

drivers/i2c/busses/i2c-at91.c

@@ -92,6 +92,8 @@
 
 #define AT91_TWI_FILTR		0x0044
 #define AT91_TWI_FILTR_FILT	BIT(0)
+#define AT91_TWI_FILTR_PADFEN	BIT(1)
+#define AT91_TWI_FILTR_PADFCFG	BIT(2)
 #define AT91_TWI_FILTR_THRES(v)		((v) << 8)
 #define AT91_TWI_FILTR_THRES_MASK	GENMASK(10, 8)
 
@@ -121,6 +123,7 @@ struct at91_twi_pdata {
 	bool has_hold_field;
 	bool has_dig_filtr;
 	bool has_adv_dig_filtr;
+	bool has_ana_filtr;
 	struct at_dma_slave dma_slave;
 };
 
@@ -154,6 +157,7 @@ struct at91_twi_dev {
 	u32 fifo_size;
 	struct at91_twi_dma dma;
 	bool enable_dig_filt;
+	bool enable_ana_filt;
 };
 
 static unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg)
@@ -185,6 +189,7 @@ static void at91_twi_irq_restore(struct at91_twi_dev *dev)
 static void at91_init_twi_bus(struct at91_twi_dev *dev)
 {
 	struct at91_twi_pdata *pdata = dev->pdata;
+	u32 filtr = 0;
 
 	at91_disable_twi_interrupts(dev);
 	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
@@ -197,13 +202,19 @@ static void at91_init_twi_bus(struct at91_twi_dev *dev)
 
 	/* enable digital filter */
 	if (pdata->has_dig_filtr && dev->enable_dig_filt)
-		at91_twi_write(dev, AT91_TWI_FILTR, AT91_TWI_FILTR_FILT);
+		filtr |= AT91_TWI_FILTR_FILT;
 
 	/* enable advanced digital filter */
 	if (pdata->has_adv_dig_filtr && dev->enable_dig_filt)
-		at91_twi_write(dev, AT91_TWI_FILTR, AT91_TWI_FILTR_FILT |
-			       (AT91_TWI_FILTR_THRES(7) &
-				AT91_TWI_FILTR_THRES_MASK));
+		filtr |= AT91_TWI_FILTR_FILT |
+			 (AT91_TWI_FILTR_THRES(7) & AT91_TWI_FILTR_THRES_MASK);
+
+	/* enable analog filter */
+	if (pdata->has_ana_filtr && dev->enable_ana_filt)
+		filtr |= AT91_TWI_FILTR_PADFEN | AT91_TWI_FILTR_PADFCFG;
+
+	if (filtr)
+		at91_twi_write(dev, AT91_TWI_FILTR, filtr);
 }
 
 /*
@@ -853,6 +864,7 @@ static struct at91_twi_pdata at91rm9200_config = {
 	.has_hold_field = false,
 	.has_dig_filtr = false,
 	.has_adv_dig_filtr = false,
+	.has_ana_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9261_config = {
@@ -863,6 +875,7 @@ static struct at91_twi_pdata at91sam9261_config = {
 	.has_hold_field = false,
 	.has_dig_filtr = false,
 	.has_adv_dig_filtr = false,
+	.has_ana_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9260_config = {
@@ -873,6 +886,7 @@ static struct at91_twi_pdata at91sam9260_config = {
 	.has_hold_field = false,
 	.has_dig_filtr = false,
 	.has_adv_dig_filtr = false,
+	.has_ana_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9g20_config = {
@@ -883,6 +897,7 @@ static struct at91_twi_pdata at91sam9g20_config = {
 	.has_hold_field = false,
 	.has_dig_filtr = false,
 	.has_adv_dig_filtr = false,
+	.has_ana_filtr = false,
 };
 
 static struct at91_twi_pdata at91sam9g10_config = {
@@ -893,6 +908,7 @@ static struct at91_twi_pdata at91sam9g10_config = {
 	.has_hold_field = false,
 	.has_dig_filtr = false,
 	.has_adv_dig_filtr = false,
+	.has_ana_filtr = false,
 };
 
 static const struct platform_device_id at91_twi_devtypes[] = {
@@ -925,6 +941,7 @@ static struct at91_twi_pdata at91sam9x5_config = {
 	.has_hold_field = false,
 	.has_dig_filtr = false,
 	.has_adv_dig_filtr = false,
+	.has_ana_filtr = false,
 };
 
 static struct at91_twi_pdata sama5d4_config = {
@@ -935,6 +952,7 @@ static struct at91_twi_pdata sama5d4_config = {
 	.has_hold_field = true,
 	.has_dig_filtr = true,
 	.has_adv_dig_filtr = false,
+	.has_ana_filtr = false,
 };
 
 static struct at91_twi_pdata sama5d2_config = {
@@ -945,6 +963,7 @@ static struct at91_twi_pdata sama5d2_config = {
 	.has_hold_field = true,
 	.has_dig_filtr = true,
 	.has_adv_dig_filtr = true,
+	.has_ana_filtr = true,
 };
 
 static struct at91_twi_pdata sam9x60_config = {
@@ -955,6 +974,7 @@ static struct at91_twi_pdata sam9x60_config = {
 	.has_hold_field = true,
 	.has_dig_filtr = true,
 	.has_adv_dig_filtr = true,
+	.has_ana_filtr = true,
 };
 
 static const struct of_device_id atmel_twi_dt_ids[] = {
@@ -1157,6 +1177,9 @@ static int at91_twi_probe(struct platform_device *pdev)
 	dev->enable_dig_filt = of_property_read_bool(pdev->dev.of_node,
 						     "enable-dig-filt");
 
+	dev->enable_ana_filt = of_property_read_bool(pdev->dev.of_node,
+						     "enable-ana-filt");
+
 	at91_calc_twi_clock(dev, bus_clk_rate);
 	at91_init_twi_bus(dev);