[PATCH v2 linux dev-4.13 1/2] fsi/gpio: Include command build in locked section

[PATCH v2 linux dev-4.13 1/2] fsi/gpio: Include command build in locked section

[Jeremy Kerr]

For implementing relative addressing mode, we'll need to build a command
that is coherent with CFAM state. To do that, include the
build_command_* functions in the locked section of read/write/term.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
---
 drivers/fsi/fsi-master-gpio.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
index 029b0a5b6d89..1723fe4284b0 100644
--- a/drivers/fsi/fsi-master-gpio.c
+++ b/drivers/fsi/fsi-master-gpio.c
@@ -457,14 +457,10 @@ static int fsi_master_gpio_xfer(struct fsi_master_gpio *master, uint8_t slave,
 {
 	int rc;
 
-	mutex_lock(&master->cmd_lock);
-
 	rc = send_request(master, cmd);
 	if (!rc)
 		rc = poll_for_response(master, slave, resp_len, resp);
 
-	mutex_unlock(&master->cmd_lock);
-
 	return rc;
 }
 
@@ -473,12 +469,17 @@ static int fsi_master_gpio_read(struct fsi_master *_master, int link,
 {
 	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
 	struct fsi_gpio_msg cmd;
+	int rc;
 
 	if (link != 0)
 		return -ENODEV;
 
+	mutex_lock(&master->cmd_lock);
 	build_abs_ar_command(&cmd, id, addr, size, NULL);
-	return fsi_master_gpio_xfer(master, id, &cmd, size, val);
+	rc = fsi_master_gpio_xfer(master, id, &cmd, size, val);
+	mutex_unlock(&master->cmd_lock);
+
+	return rc;
 }
 
 static int fsi_master_gpio_write(struct fsi_master *_master, int link,
@@ -486,12 +487,17 @@ static int fsi_master_gpio_write(struct fsi_master *_master, int link,
 {
 	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
 	struct fsi_gpio_msg cmd;
+	int rc;
 
 	if (link != 0)
 		return -ENODEV;
 
+	mutex_lock(&master->cmd_lock);
 	build_abs_ar_command(&cmd, id, addr, size, val);
-	return fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
+	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
+	mutex_unlock(&master->cmd_lock);
+
+	return rc;
 }
 
 static int fsi_master_gpio_term(struct fsi_master *_master,
@@ -499,12 +505,17 @@ static int fsi_master_gpio_term(struct fsi_master *_master,
 {
 	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
 	struct fsi_gpio_msg cmd;
+	int rc;
 
 	if (link != 0)
 		return -ENODEV;
 
+	mutex_lock(&master->cmd_lock);
 	build_term_command(&cmd, id);
-	return fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
+	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
+	mutex_unlock(&master->cmd_lock);
+
+	return rc;
 }
 
 static int fsi_master_gpio_break(struct fsi_master *_master, int link)
-- 
2.14.1

[PATCH v2 linux dev-4.13 2/2] fsi/gpio: Use relative-addressing commands

[Jeremy Kerr]

FSI CFAMs support shorter commands that use a relative (or same) address
as the last. This change introduces a last_addr to the master state, and
uses it for subsequent reads/writes, and performs relative addressing
when a subsequent read/write is in range.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
---
v2:
 - actually send real version this time
 - rebase onto shenki/fsi-speedups
---
 drivers/fsi/fsi-master-gpio.c | 102 +++++++++++++++++++++++++++++++++++++-----
 1 file changed, 91 insertions(+), 11 deletions(-)

diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
index 1723fe4284b0..8d14168d8660 100644
--- a/drivers/fsi/fsi-master-gpio.c
+++ b/drivers/fsi/fsi-master-gpio.c
@@ -28,6 +28,8 @@
 #define	FSI_GPIO_CMD_DPOLL      0x2
 #define	FSI_GPIO_CMD_TERM	0x3f
 #define FSI_GPIO_CMD_ABS_AR	0x4
+#define FSI_GPIO_CMD_REL_AR	0x5
+#define FSI_GPIO_CMD_SAME_AR	0x3	/* but only a 2-bit opcode... */
 
 #define	FSI_GPIO_DPOLL_CLOCKS	100      /* < 21 will cause slave to hang */
 
@@ -51,6 +53,8 @@
 #define	FSI_GPIO_MSG_RESPID_SIZE	2
 #define	FSI_GPIO_PRIME_SLAVE_CLOCKS	20
 
+#define LAST_ADDR_INVALID		0x1
+
 struct fsi_master_gpio {
 	struct fsi_master	master;
 	struct device		*dev;
@@ -63,6 +67,7 @@ struct fsi_master_gpio {
 	struct gpio_desc	*gpio_mux;	/* Mux control */
 	bool			external_mode;
 	bool			no_delays;
+	uint32_t		last_addr;
 };
 
 #define CREATE_TRACE_POINTS
@@ -199,22 +204,89 @@ static void msg_push_crc(struct fsi_gpio_msg *msg)
 	msg_push_bits(msg, crc, 4);
 }
 
+static bool check_same_address(struct fsi_master_gpio *master, int id,
+		uint32_t addr)
+{
+	/* this will also handle LAST_ADDR_INVALID */
+	return master->last_addr == (((id & 0x3) << 21) | (addr & ~0x3));
+}
+
+static bool check_relative_address(struct fsi_master_gpio *master, int id,
+		uint32_t addr, uint32_t *rel_addrp)
+{
+	uint32_t last_addr = master->last_addr;
+	int32_t rel_addr;
+
+	if (last_addr == LAST_ADDR_INVALID)
+		return false;
+
+	/* We may be in 23-bit addressing mode, which uses the id as the
+	 * top two address bits. So, if we're referencing a different ID,
+	 * use absolute addresses.
+	 */
+	if (((last_addr >> 21) & 0x3) != id)
+		return false;
+
+	/* remove the top two bits from any 23-bit addressing */
+	last_addr &= (1 << 21) - 1;
+
+	/* We know that the addresses are limited to 21 bits, so this won't
+	 * overflow the signed rel_addr */
+	rel_addr = addr - last_addr;
+	if (rel_addr > 255 || rel_addr < -256)
+		return false;
+
+	*rel_addrp = (uint32_t)rel_addr;
+
+	return true;
+}
+
+static void last_address_update(struct fsi_master_gpio *master,
+		int id, bool valid, uint32_t addr)
+{
+	if (!valid)
+		master->last_addr = LAST_ADDR_INVALID;
+	else
+		master->last_addr = ((id & 0x3) << 21) | (addr & ~0x3);
+}
+
 /*
- * Encode an Absolute Address command
+ * Encode an Absolute/Relative/Same Address command
  */
-static void build_abs_ar_command(struct fsi_gpio_msg *cmd,
-		uint8_t id, uint32_t addr, size_t size, const void *data)
+static void build_ar_command(struct fsi_master_gpio *master,
+		struct fsi_gpio_msg *cmd, uint8_t id,
+		uint32_t addr, size_t size, const void *data)
 {
+	int i, addr_bits, opcode_bits;
 	bool write = !!data;
-	uint8_t ds;
-	int i;
+	uint8_t ds, opcode;
+	uint32_t rel_addr;
 
 	cmd->bits = 0;
 	cmd->msg = 0;
 
-	msg_push_bits(cmd, id, 2);
-	msg_push_bits(cmd, FSI_GPIO_CMD_ABS_AR, 3);
-	msg_push_bits(cmd, write ? 0 : 1, 1);
+	/* we have 21 bits of address max */
+	addr &= ((1 << 21) - 1);
+
+	/* cmd opcodes are variable length - SAME_AR is only two bits */
+	opcode_bits = 3;
+
+	if (check_same_address(master, id, addr)) {
+		/* we still address the byte offset within the word */
+		addr_bits = 2;
+		opcode_bits = 2;
+		opcode = FSI_GPIO_CMD_SAME_AR;
+
+	} else if (check_relative_address(master, id, addr, &rel_addr)) {
+		/* 8 bits plus sign */
+		addr_bits = 9;
+		addr = rel_addr;
+		opcode = FSI_GPIO_CMD_REL_AR;
+
+	} else {
+		addr_bits = 21;
+		opcode = FSI_GPIO_CMD_ABS_AR;
+	}
 
 	/*
 	 * The read/write size is encoded in the lower bits of the address
@@ -231,7 +303,10 @@ static void build_abs_ar_command(struct fsi_gpio_msg *cmd,
 	if (size == 4)
 		addr |= 1;
 
-	msg_push_bits(cmd, addr & ((1 << 21) - 1), 21);
+	msg_push_bits(cmd, id, 2);
+	msg_push_bits(cmd, opcode, opcode_bits);
+	msg_push_bits(cmd, write ? 0 : 1, 1);
+	msg_push_bits(cmd, addr, addr_bits);
 	msg_push_bits(cmd, ds, 1);
 	for (i = 0; write && i < size; i++)
 		msg_push_bits(cmd, ((uint8_t *)data)[i], 8);
@@ -475,8 +550,9 @@ static int fsi_master_gpio_read(struct fsi_master *_master, int link,
 		return -ENODEV;
 
 	mutex_lock(&master->cmd_lock);
-	build_abs_ar_command(&cmd, id, addr, size, NULL);
+	build_ar_command(master, &cmd, id, addr, size, NULL);
 	rc = fsi_master_gpio_xfer(master, id, &cmd, size, val);
+	last_address_update(master, id, rc == 0, addr);
 	mutex_unlock(&master->cmd_lock);
 
 	return rc;
@@ -493,8 +569,9 @@ static int fsi_master_gpio_write(struct fsi_master *_master, int link,
 		return -ENODEV;
 
 	mutex_lock(&master->cmd_lock);
-	build_abs_ar_command(&cmd, id, addr, size, val);
+	build_ar_command(master, &cmd, id, addr, size, val);
 	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
+	last_address_update(master, id, rc == 0, addr);
 	mutex_unlock(&master->cmd_lock);
 
 	return rc;
@@ -513,6 +590,7 @@ static int fsi_master_gpio_term(struct fsi_master *_master,
 	mutex_lock(&master->cmd_lock);
 	build_term_command(&cmd, id);
 	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
+	last_address_update(master, id, false, 0);
 	mutex_unlock(&master->cmd_lock);
 
 	return rc;
@@ -546,6 +624,7 @@ static int fsi_master_gpio_break(struct fsi_master *_master, int link)
 	clock_toggle(master, FSI_POST_BREAK_CLOCKS);
 
 	spin_unlock_irqrestore(&master->bit_lock, flags);
+	last_address_update(master, 0, false, 0);
 	mutex_unlock(&master->cmd_lock);
 
 	/* Wait for logic reset to take effect */
@@ -656,6 +735,7 @@ static int fsi_master_gpio_probe(struct platform_device *pdev)
 	master->dev = &pdev->dev;
 	master->master.dev.parent = master->dev;
 	master->master.dev.of_node = of_node_get(dev_of_node(master->dev));
+	master->last_addr = LAST_ADDR_INVALID;
 
 	gpio = devm_gpiod_get(&pdev->dev, "clock", 0);
 	if (IS_ERR(gpio)) {
-- 
2.14.1

Re: [PATCH v2 linux dev-4.13 1/2] fsi/gpio: Include command build in locked section

[Christopher Bostic]

Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>


On 5/10/18 4:22 AM, Jeremy Kerr wrote:
> For implementing relative addressing mode, we'll need to build a command
> that is coherent with CFAM state. To do that, include the
> build_command_* functions in the locked section of read/write/term.
>
> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
> ---
>   drivers/fsi/fsi-master-gpio.c | 25 ++++++++++++++++++-------
>   1 file changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
> index 029b0a5b6d89..1723fe4284b0 100644
> --- a/drivers/fsi/fsi-master-gpio.c
> +++ b/drivers/fsi/fsi-master-gpio.c
> @@ -457,14 +457,10 @@ static int fsi_master_gpio_xfer(struct fsi_master_gpio *master, uint8_t slave,
>   {
>   	int rc;
>
> -	mutex_lock(&master->cmd_lock);
> -
>   	rc = send_request(master, cmd);
>   	if (!rc)
>   		rc = poll_for_response(master, slave, resp_len, resp);
>
> -	mutex_unlock(&master->cmd_lock);
> -
>   	return rc;
>   }
>
> @@ -473,12 +469,17 @@ static int fsi_master_gpio_read(struct fsi_master *_master, int link,
>   {
>   	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
>   	struct fsi_gpio_msg cmd;
> +	int rc;
>
>   	if (link != 0)
>   		return -ENODEV;
>
> +	mutex_lock(&master->cmd_lock);
>   	build_abs_ar_command(&cmd, id, addr, size, NULL);
> -	return fsi_master_gpio_xfer(master, id, &cmd, size, val);
> +	rc = fsi_master_gpio_xfer(master, id, &cmd, size, val);
> +	mutex_unlock(&master->cmd_lock);
> +
> +	return rc;
>   }
>
>   static int fsi_master_gpio_write(struct fsi_master *_master, int link,
> @@ -486,12 +487,17 @@ static int fsi_master_gpio_write(struct fsi_master *_master, int link,
>   {
>   	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
>   	struct fsi_gpio_msg cmd;
> +	int rc;
>
>   	if (link != 0)
>   		return -ENODEV;
>
> +	mutex_lock(&master->cmd_lock);
>   	build_abs_ar_command(&cmd, id, addr, size, val);
> -	return fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
> +	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
> +	mutex_unlock(&master->cmd_lock);
> +
> +	return rc;
>   }
>
>   static int fsi_master_gpio_term(struct fsi_master *_master,
> @@ -499,12 +505,17 @@ static int fsi_master_gpio_term(struct fsi_master *_master,
>   {
>   	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
>   	struct fsi_gpio_msg cmd;
> +	int rc;
>
>   	if (link != 0)
>   		return -ENODEV;
>
> +	mutex_lock(&master->cmd_lock);
>   	build_term_command(&cmd, id);
> -	return fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
> +	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
> +	mutex_unlock(&master->cmd_lock);
> +
> +	return rc;
>   }
>
>   static int fsi_master_gpio_break(struct fsi_master *_master, int link)

Re: [PATCH v2 linux dev-4.13 2/2] fsi/gpio: Use relative-addressing commands

[Christopher Bostic]

Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>


On 5/10/18 4:22 AM, Jeremy Kerr wrote:
> FSI CFAMs support shorter commands that use a relative (or same) address
> as the last. This change introduces a last_addr to the master state, and
> uses it for subsequent reads/writes, and performs relative addressing
> when a subsequent read/write is in range.
>
> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
> ---
> v2:
>   - actually send real version this time
>   - rebase onto shenki/fsi-speedups
> ---
>   drivers/fsi/fsi-master-gpio.c | 102 +++++++++++++++++++++++++++++++++++++-----
>   1 file changed, 91 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
> index 1723fe4284b0..8d14168d8660 100644
> --- a/drivers/fsi/fsi-master-gpio.c
> +++ b/drivers/fsi/fsi-master-gpio.c
> @@ -28,6 +28,8 @@
>   #define	FSI_GPIO_CMD_DPOLL      0x2
>   #define	FSI_GPIO_CMD_TERM	0x3f
>   #define FSI_GPIO_CMD_ABS_AR	0x4
> +#define FSI_GPIO_CMD_REL_AR	0x5
> +#define FSI_GPIO_CMD_SAME_AR	0x3	/* but only a 2-bit opcode... */
>
>   #define	FSI_GPIO_DPOLL_CLOCKS	100      /* < 21 will cause slave to hang */
>
> @@ -51,6 +53,8 @@
>   #define	FSI_GPIO_MSG_RESPID_SIZE	2
>   #define	FSI_GPIO_PRIME_SLAVE_CLOCKS	20
>
> +#define LAST_ADDR_INVALID		0x1
> +
>   struct fsi_master_gpio {
>   	struct fsi_master	master;
>   	struct device		*dev;
> @@ -63,6 +67,7 @@ struct fsi_master_gpio {
>   	struct gpio_desc	*gpio_mux;	/* Mux control */
>   	bool			external_mode;
>   	bool			no_delays;
> +	uint32_t		last_addr;
>   };
>
>   #define CREATE_TRACE_POINTS
> @@ -199,22 +204,89 @@ static void msg_push_crc(struct fsi_gpio_msg *msg)
>   	msg_push_bits(msg, crc, 4);
>   }
>
> +static bool check_same_address(struct fsi_master_gpio *master, int id,
> +		uint32_t addr)
> +{
> +	/* this will also handle LAST_ADDR_INVALID */
> +	return master->last_addr == (((id & 0x3) << 21) | (addr & ~0x3));
> +}
> +
> +static bool check_relative_address(struct fsi_master_gpio *master, int id,
> +		uint32_t addr, uint32_t *rel_addrp)
> +{
> +	uint32_t last_addr = master->last_addr;
> +	int32_t rel_addr;
> +
> +	if (last_addr == LAST_ADDR_INVALID)
> +		return false;
> +
> +	/* We may be in 23-bit addressing mode, which uses the id as the
> +	 * top two address bits. So, if we're referencing a different ID,
> +	 * use absolute addresses.
> +	 */
> +	if (((last_addr >> 21) & 0x3) != id)
> +		return false;
> +
> +	/* remove the top two bits from any 23-bit addressing */
> +	last_addr &= (1 << 21) - 1;
> +
> +	/* We know that the addresses are limited to 21 bits, so this won't
> +	 * overflow the signed rel_addr */
> +	rel_addr = addr - last_addr;
> +	if (rel_addr > 255 || rel_addr < -256)
> +		return false;
> +
> +	*rel_addrp = (uint32_t)rel_addr;
> +
> +	return true;
> +}
> +
> +static void last_address_update(struct fsi_master_gpio *master,
> +		int id, bool valid, uint32_t addr)
> +{
> +	if (!valid)
> +		master->last_addr = LAST_ADDR_INVALID;
> +	else
> +		master->last_addr = ((id & 0x3) << 21) | (addr & ~0x3);
> +}
> +
>   /*
> - * Encode an Absolute Address command
> + * Encode an Absolute/Relative/Same Address command
>    */
> -static void build_abs_ar_command(struct fsi_gpio_msg *cmd,
> -		uint8_t id, uint32_t addr, size_t size, const void *data)
> +static void build_ar_command(struct fsi_master_gpio *master,
> +		struct fsi_gpio_msg *cmd, uint8_t id,
> +		uint32_t addr, size_t size, const void *data)
>   {
> +	int i, addr_bits, opcode_bits;
>   	bool write = !!data;
> -	uint8_t ds;
> -	int i;
> +	uint8_t ds, opcode;
> +	uint32_t rel_addr;
>
>   	cmd->bits = 0;
>   	cmd->msg = 0;
>
> -	msg_push_bits(cmd, id, 2);
> -	msg_push_bits(cmd, FSI_GPIO_CMD_ABS_AR, 3);
> -	msg_push_bits(cmd, write ? 0 : 1, 1);
> +	/* we have 21 bits of address max */
> +	addr &= ((1 << 21) - 1);
> +
> +	/* cmd opcodes are variable length - SAME_AR is only two bits */
> +	opcode_bits = 3;
> +
> +	if (check_same_address(master, id, addr)) {
> +		/* we still address the byte offset within the word */
> +		addr_bits = 2;
> +		opcode_bits = 2;
> +		opcode = FSI_GPIO_CMD_SAME_AR;
> +
> +	} else if (check_relative_address(master, id, addr, &rel_addr)) {
> +		/* 8 bits plus sign */
> +		addr_bits = 9;
> +		addr = rel_addr;
> +		opcode = FSI_GPIO_CMD_REL_AR;
> +
> +	} else {
> +		addr_bits = 21;
> +		opcode = FSI_GPIO_CMD_ABS_AR;
> +	}
>
>   	/*
>   	 * The read/write size is encoded in the lower bits of the address
> @@ -231,7 +303,10 @@ static void build_abs_ar_command(struct fsi_gpio_msg *cmd,
>   	if (size == 4)
>   		addr |= 1;
>
> -	msg_push_bits(cmd, addr & ((1 << 21) - 1), 21);
> +	msg_push_bits(cmd, id, 2);
> +	msg_push_bits(cmd, opcode, opcode_bits);
> +	msg_push_bits(cmd, write ? 0 : 1, 1);
> +	msg_push_bits(cmd, addr, addr_bits);
>   	msg_push_bits(cmd, ds, 1);
>   	for (i = 0; write && i < size; i++)
>   		msg_push_bits(cmd, ((uint8_t *)data)[i], 8);
> @@ -475,8 +550,9 @@ static int fsi_master_gpio_read(struct fsi_master *_master, int link,
>   		return -ENODEV;
>
>   	mutex_lock(&master->cmd_lock);
> -	build_abs_ar_command(&cmd, id, addr, size, NULL);
> +	build_ar_command(master, &cmd, id, addr, size, NULL);
>   	rc = fsi_master_gpio_xfer(master, id, &cmd, size, val);
> +	last_address_update(master, id, rc == 0, addr);
>   	mutex_unlock(&master->cmd_lock);
>
>   	return rc;
> @@ -493,8 +569,9 @@ static int fsi_master_gpio_write(struct fsi_master *_master, int link,
>   		return -ENODEV;
>
>   	mutex_lock(&master->cmd_lock);
> -	build_abs_ar_command(&cmd, id, addr, size, val);
> +	build_ar_command(master, &cmd, id, addr, size, val);
>   	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
> +	last_address_update(master, id, rc == 0, addr);
>   	mutex_unlock(&master->cmd_lock);
>
>   	return rc;
> @@ -513,6 +590,7 @@ static int fsi_master_gpio_term(struct fsi_master *_master,
>   	mutex_lock(&master->cmd_lock);
>   	build_term_command(&cmd, id);
>   	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
> +	last_address_update(master, id, false, 0);
>   	mutex_unlock(&master->cmd_lock);
>
>   	return rc;
> @@ -546,6 +624,7 @@ static int fsi_master_gpio_break(struct fsi_master *_master, int link)
>   	clock_toggle(master, FSI_POST_BREAK_CLOCKS);
>
>   	spin_unlock_irqrestore(&master->bit_lock, flags);
> +	last_address_update(master, 0, false, 0);
>   	mutex_unlock(&master->cmd_lock);
>
>   	/* Wait for logic reset to take effect */
> @@ -656,6 +735,7 @@ static int fsi_master_gpio_probe(struct platform_device *pdev)
>   	master->dev = &pdev->dev;
>   	master->master.dev.parent = master->dev;
>   	master->master.dev.of_node = of_node_get(dev_of_node(master->dev));
> +	master->last_addr = LAST_ADDR_INVALID;
>
>   	gpio = devm_gpiod_get(&pdev->dev, "clock", 0);
>   	if (IS_ERR(gpio)) {