[PATCH 1/4] NFC: trf7970a: Add support for gpio as SS

[Geoff Lansberry <geoff@kuvee.com>]

Signed-off-by: Geoff Lansberry <geoff@kuvee.com>
---
 .../devicetree/bindings/net/nfc/trf7970a.txt       |  2 ++
 drivers/nfc/trf7970a.c                             | 33 ++++++++++++++++++++--
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
index 32b35a0..09c5056 100644
--- a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
+++ b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
@@ -7,6 +7,7 @@ Required properties:
 - interrupts: A single interrupt specifier.
 - ti,enable-gpios: Two GPIO entries used for 'EN' and 'EN2' pins on the
   TRF7970A.
+- ti,ss-gpio: GPIO entry used for active low SS (spi slave select) on the TRF7970A
 - vin-supply: Regulator for supply voltage to VIN pin
 
 Optional SoC Specific Properties:
@@ -37,6 +38,7 @@ Example (for ARM-based BeagleBone with TRF7970A on SPI1):
 		interrupts = <14 0>;
 		ti,enable-gpios = <&gpio2 2 GPIO_ACTIVE_LOW>,
 				  <&gpio2 5 GPIO_ACTIVE_LOW>;
+		ti,ss-gpio = <&gpio2 4 GPIO_ACTIVE_HIGH>;
 		vin-supply = <&ldo3_reg>;
 		vin-voltage-override = <5000000>;
 		autosuspend-delay = <30000>;
diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c
index 10842b7..2c3530a 100644
--- a/drivers/nfc/trf7970a.c
+++ b/drivers/nfc/trf7970a.c
@@ -450,6 +450,7 @@ struct trf7970a {
 	bool				adjust_resp_len;
 	int				en2_gpio;
 	int				en_gpio;
+	int				ss_gpio;
 	struct mutex			lock;
 	unsigned int			timeout;
 	bool				ignore_timeout;
@@ -462,9 +463,11 @@ static int trf7970a_cmd(struct trf7970a *trf, u8 opcode)
 	u8 cmd = TRF7970A_CMD_BIT_CTRL | TRF7970A_CMD_BIT_OPCODE(opcode);
 	int ret;
 
+	gpio_set_value(trf->ss_gpio, 0);
 	dev_dbg(trf->dev, "cmd: 0x%x\n", cmd);
 
 	ret = spi_write(trf->spi, &cmd, 1);
+	gpio_set_value(trf->ss_gpio, 1);
 	if (ret)
 		dev_err(trf->dev, "%s - cmd: 0x%x, ret: %d\n", __func__, cmd,
 				ret);
@@ -476,7 +479,9 @@ static int trf7970a_read(struct trf7970a *trf, u8 reg, u8 *val)
 	u8 addr = TRF7970A_CMD_BIT_RW | reg;
 	int ret;
 
+	gpio_set_value(trf->ss_gpio, 0);
 	ret = spi_write_then_read(trf->spi, &addr, 1, val, 1);
+	gpio_set_value(trf->ss_gpio, 1);
 	if (ret)
 		dev_err(trf->dev, "%s - addr: 0x%x, ret: %d\n", __func__, addr,
 				ret);
@@ -493,6 +498,7 @@ static int trf7970a_read_cont(struct trf7970a *trf, u8 reg, u8 *buf, size_t len)
 	struct spi_message m;
 	int ret;
 
+	gpio_set_value(trf->ss_gpio, 0);
 	dev_dbg(trf->dev, "read_cont(0x%x, %zd)\n", addr, len);
 
 	spi_message_init(&m);
@@ -508,6 +514,7 @@ static int trf7970a_read_cont(struct trf7970a *trf, u8 reg, u8 *buf, size_t len)
 	spi_message_add_tail(&t[1], &m);
 
 	ret = spi_sync(trf->spi, &m);
+	gpio_set_value(trf->ss_gpio, 1);
 	if (ret)
 		dev_err(trf->dev, "%s - addr: 0x%x, ret: %d\n", __func__, addr,
 				ret);
@@ -519,9 +526,11 @@ static int trf7970a_write(struct trf7970a *trf, u8 reg, u8 val)
 	u8 buf[2] = { reg, val };
 	int ret;
 
+	gpio_set_value(trf->ss_gpio, 0);
 	dev_dbg(trf->dev, "write(0x%x): 0x%x\n", reg, val);
 
 	ret = spi_write(trf->spi, buf, 2);
+	gpio_set_value(trf->ss_gpio, 1);
 	if (ret)
 		dev_err(trf->dev, "%s - write: 0x%x 0x%x, ret: %d\n", __func__,
 				buf[0], buf[1], ret);
@@ -535,6 +544,7 @@ static int trf7970a_read_irqstatus(struct trf7970a *trf, u8 *status)
 	u8 buf[2];
 	u8 addr;
 
+	gpio_set_value(trf->ss_gpio, 0);
 	addr = TRF7970A_IRQ_STATUS | TRF7970A_CMD_BIT_RW;
 
 	if (trf->quirks & TRF7970A_QUIRK_IRQ_STATUS_READ) {
@@ -544,6 +554,7 @@ static int trf7970a_read_irqstatus(struct trf7970a *trf, u8 *status)
 		ret = spi_write_then_read(trf->spi, &addr, 1, buf, 1);
 	}
 
+	gpio_set_value(trf->ss_gpio, 1);
 	if (ret)
 		dev_err(trf->dev, "%s - irqstatus: Status read failed: %d\n",
 				__func__, ret);
@@ -559,6 +570,7 @@ static int trf7970a_read_target_proto(struct trf7970a *trf, u8 *target_proto)
 	u8 buf[2];
 	u8 addr;
 
+	gpio_set_value(trf->ss_gpio, 0);
 	addr = TRF79070A_NFC_TARGET_PROTOCOL | TRF7970A_CMD_BIT_RW |
 		TRF7970A_CMD_BIT_CONTINUOUS;
 
@@ -569,6 +581,7 @@ static int trf7970a_read_target_proto(struct trf7970a *trf, u8 *target_proto)
 	else
 		*target_proto = buf[0];
 
+	gpio_set_value(trf->ss_gpio, 1);
 	return ret;
 }
 
@@ -663,6 +676,7 @@ static int trf7970a_transmit(struct trf7970a *trf, struct sk_buff *skb,
 	print_hex_dump_debug("trf7970a tx data: ", DUMP_PREFIX_NONE,
 			16, 1, skb->data, len, false);
 
+	gpio_set_value(trf->ss_gpio, 0);
 	spi_message_init(&m);
 
 	memset(&t, 0, sizeof(t));
@@ -679,7 +693,7 @@ static int trf7970a_transmit(struct trf7970a *trf, struct sk_buff *skb,
 	if (ret) {
 		dev_err(trf->dev, "%s - Can't send tx data: %d\n", __func__,
 				ret);
-		return ret;
+		goto out_err;
 	}
 
 	skb_pull(skb, len);
@@ -706,7 +720,9 @@ static int trf7970a_transmit(struct trf7970a *trf, struct sk_buff *skb,
 
 	schedule_delayed_work(&trf->timeout_work, msecs_to_jiffies(timeout));
 
-	return 0;
+out_err:
+	gpio_set_value(trf->ss_gpio, 1);
+	return ret;
 }
 
 static void trf7970a_fill_fifo(struct trf7970a *trf)
@@ -2039,6 +2055,19 @@ static int trf7970a_probe(struct spi_device *spi)
 		return ret;
 	}
 
+	trf->ss_gpio = of_get_named_gpio(np, "ti,ss-gpio", 0);
+	if (!gpio_is_valid(trf->ss_gpio)) {
+		dev_err(trf->dev, "No SS GPIO property\n");
+		return trf->ss_gpio;
+	}
+
+	ret = devm_gpio_request_one(trf->dev, trf->ss_gpio,
+			GPIOF_DIR_OUT | GPIOF_INIT_HIGH, "trf7970a SS");
+	if (ret) {
+		dev_err(trf->dev, "Can't request SS GPIO: %d\n", ret);
+		return ret;
+	}
+
 	if (of_property_read_bool(np, "en2-rf-quirk"))
 		trf->quirks |= TRF7970A_QUIRK_EN2_MUST_STAY_LOW;
 
-- 
1.9.1