exynos: Support a delay after deactivate for SPI

For devices that need some time to react after a spi transaction finishes, add the ability to set a delay.

Implement this as a delay on the first/next transaction to avoid any delay in the fairly common case where a SPI transaction is followed by other processing.

Based on:
"[U-Boot] [PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"

Signed-off-by Simon Glass <[email protected]>

Signed-off-by Rajeshwari Shinde <[email protected]>

---
Changes in V2:
- None.
Changes in V3:
- Rebased on "[PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"

  drivers/spi/exynos_spi.c |   19 +++++++++++++++++++
  1 files changed, 19 insertions(+), 0 deletions(-)

drivers/spi/exynos_spi.c +5 -0

index 01378d0..03cf503 100644
@@ -38,6 +38,7 @@ struct spi_bus {
  	struct exynos_spi *regs;
  	int inited;		/* 1 if this bus is ready for use */
  	int node;
+	uint deactivate_delay_us;	/* Delay to wait after deactivate */
  };
 
  /* A list of spi buses that we know about */

@@ -52,6 +53,8 @@ struct exynos_spi_slave {
  	enum periph_id periph_id;	/* Peripheral ID for this device */
  	unsigned int fifo_size;
  	int skip_preamble;
+	struct spi_bus *bus;		/* Pointer to our SPI bus info */
+	ulong last_transaction_us;	/* Time of last transaction end */
  };
 
  static struct spi_bus *spi_get_bus(unsigned dev_index)

@@ -97,6 +100,7 @@ struct spi_slave *spi_setup_slave(unsigned int busnum, unsigned int cs,
  	}
 
  	bus = &spi_bus[busnum];
+	spi_slave->bus = bus;
  	spi_slave->regs = bus->regs;
  	spi_slave->mode = mode;
  	spi_slave->periph_id = bus->periph_id;

@@ -107,6 +111,7 @@ struct spi_slave *spi_setup_slave(unsigned int busnum, unsigned int cs,
  		spi_slave->fifo_size = 256;
 
  	spi_slave->skip_preamble = 0;
+	spi_slave->last_transaction_us = timer_get_us();
 
  	spi_slave->freq = bus->frequency;
  	if (max_hz)

@@ -371,9 +376,21 @@ void spi_cs_activate(struct spi_slave *slave)
  {

drivers/spi/exynos_spi.c +4 -0

  	clrbits_le32(&spi_slave->regs->cs_reg, SPI_SLAVE_SIG_INACT);
  	debug("Activate CS, bus %d\n", spi_slave->slave.bus);
  	spi_slave->skip_preamble = spi_slave->mode & SPI_PREAMBLE;
+
+	/* Remember time of this transaction so we can honour the bus delay */
+	if (spi_slave->bus->deactivate_delay_us)
+		spi_slave->last_transaction_us = timer_get_us();
  }
 
  /**

Hi,

Quoted 10 lines · Rajeshwari Shinde

For devices that need some time to react after a spi transaction finishes, add the ability to set a delay.

Implement this as a delay on the first/next transaction to avoid any delay in the fairly common case where a SPI transaction is followed by other processing.

Based on:
"[U-Boot] [PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"

Please use the below format for referring previous commits ex:
"<PREVIOUS_COMMIT_HEAD>"
(sha1: PREVIOUS_COMMIT_ID)

in this case
"spi: exynos: Support SPI_PREAMBLE mode" (sha1: e4eaef8910df805d511b1cb9b2caaf**a7d2827fdc)

Quoted 59 lines

Signed-off-by Simon Glass <[email protected]>

Signed-off-by Rajeshwari Shinde <[email protected]>

---
Changes in V2:
- None.
Changes in V3:
- Rebased on "[PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"

  drivers/spi/exynos_spi.c |   19 +++++++++++++++++++
  1 files changed, 19 insertions(+), 0 deletions(-)

drivers/spi/exynos_spi.c +1 -0

index 01378d0..03cf503 100644
@@ -38,6 +38,7 @@ struct spi_bus {
        struct exynos_spi *regs;
        int inited;             /* 1 if this bus is ready for use */
        int node;
+       uint deactivate_delay_us;       /* Delay to wait after deactivate
 */
  };
 

/* A list of spi buses that we know about */

drivers/spi/exynos_spi.c +2 -0

@@ -52,6 +53,8 @@ struct exynos_spi_slave {
        enum periph_id periph_id;       /* Peripheral ID for this device
 */
        unsigned int fifo_size;
        int skip_preamble;
+       struct spi_bus *bus;            /* Pointer to our SPI bus info */
+       ulong last_transaction_us;      /* Time of last transaction end */
  };
 

static struct spi_bus *spi_get_bus(unsigned dev_index)

drivers/spi/exynos_spi.c +1 -0

@@ -97,6 +100,7 @@ struct spi_slave *spi_setup_slave(unsigned int busnum,
 unsigned int cs,
        }
 
        bus = &spi_bus[busnum];
+       spi_slave->bus = bus;
        spi_slave->regs = bus->regs;
        spi_slave->mode = mode;

        spi_slave->periph_id = bus->periph_id;

drivers/spi/exynos_spi.c +1 -0

@@ -107,6 +111,7 @@ struct spi_slave *spi_setup_slave(unsigned int
 busnum, unsigned int cs,
                spi_slave->fifo_size = 256;
 
        spi_slave->skip_preamble = 0;
+       spi_slave->last_transaction_us = timer_get_us();
 
        spi_slave->freq = bus->frequency;

        if (max_hz)

drivers/spi/exynos_spi.c +1 -0

@@ -371,9 +376,21 @@ void spi_cs_activate(struct spi_slave *slave)
  {
        struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
 
+       /* If it's too soon to do another transaction, wait */

drivers/spi/exynos_spi.c void spi_cs_activate(struct spi_slave *slave) · line 389

Quoted 10 lines

drivers/spi/exynos_spi.c +7 -0

+       if (spi_slave->bus->deactivate_**delay_us &&
+           spi_slave->last_transaction_**us) {
+               ulong delay_us;         /* The delay completed so far */
+               delay_us = timer_get_us() - spi_slave->last_transaction_*
 *us;
+               if (delay_us < spi_slave->bus->deactivate_**delay_us)
+                       udelay(spi_slave->bus->**deactivate_delay_us -
 delay_us);
+       }
 

Add one space

         clrbits_le32(&spi_slave->regs-**>cs_reg, SPI_SLAVE_SIG_INACT);

Quoted 18 lines

drivers/spi/exynos_spi.c +2 -0

        debug("Activate CS, bus %d\n", spi_slave->slave.bus);
        spi_slave->skip_preamble = spi_slave->mode & SPI_PREAMBLE;
+
+       /* Remember time of this transaction so we can honour the bus

delay */

drivers/spi/exynos_spi.c +4 -0

+       if (spi_slave->bus->deactivate_**delay_us)
+               spi_slave->last_transaction_us = timer_get_us();
  }
 
  /**

@@ -423,6 +440,8 @@ static int spi_get_config(const void *blob, int node,
 struct spi_bus *bus)
        /* Use 500KHz as a suitable default */
        bus->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
                                        500000);
+       bus->deactivate_delay_us = fdtdec_get_int(blob, node,
+                                       "spi-deactivate-delay", 0);
 

Quoted 4 lines

drivers/spi/exynos_spi.c +0 -0

        return 0;

  }

Was this tested, usually what is the max deactivate delay?

In this case your are passing through dts is it?

Thanks,
Jagan.

Hi Jagan,

Quoted 17 lines · Jagan Teki

Hi,

Quoted 10 lines · Rajeshwari Shinde

For devices that need some time to react after a spi transaction finishes, add the ability to set a delay.

Implement this as a delay on the first/next transaction to avoid any delay in the fairly common case where a SPI transaction is followed by other processing.

Based on:
"[U-Boot] [PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"

Quoted 8 lines

Please use the below format for referring previous commits ex:
"<PREVIOUS_COMMIT_HEAD>"
(sha1: PREVIOUS_COMMIT_ID)

in this case
"spi: exynos: Support SPI_PREAMBLE mode"
(sha1: e4eaef8910df805d511b1cb9b2caafa7d2827fdc)

I hope you don't mind me answering part of this...

Quoted 93 lines

Quoted 60 lines

Signed-off-by Simon Glass <[email protected]>

Signed-off-by Rajeshwari Shinde <[email protected]>

---
Changes in V2:
- None.
Changes in V3:
- Rebased on "[PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"

  drivers/spi/exynos_spi.c |   19 +++++++++++++++++++
  1 files changed, 19 insertions(+), 0 deletions(-)

drivers/spi/exynos_spi.c +1 -0

index 01378d0..03cf503 100644
@@ -38,6 +38,7 @@ struct spi_bus {
        struct exynos_spi *regs;
        int inited;             /* 1 if this bus is ready for use */
        int node;
+       uint deactivate_delay_us;       /* Delay to wait after deactivate
 */
  };
 

/* A list of spi buses that we know about */

drivers/spi/exynos_spi.c +2 -0

@@ -52,6 +53,8 @@ struct exynos_spi_slave {
        enum periph_id periph_id;       /* Peripheral ID for this device
 */
        unsigned int fifo_size;
        int skip_preamble;
+       struct spi_bus *bus;            /* Pointer to our SPI bus info */
+       ulong last_transaction_us;      /* Time of last transaction end
 */
  };

static struct spi_bus *spi_get_bus(unsigned dev_index)

drivers/spi/exynos_spi.c +1 -0

@@ -97,6 +100,7 @@ struct spi_slave *spi_setup_slave(unsigned int busnum,
 unsigned int cs,
        }
 
        bus = &spi_bus[busnum];
+       spi_slave->bus = bus;
        spi_slave->regs = bus->regs;
        spi_slave->mode = mode;

        spi_slave->periph_id = bus->periph_id;

drivers/spi/exynos_spi.c +1 -0

@@ -107,6 +111,7 @@ struct spi_slave *spi_setup_slave(unsigned int
 busnum, unsigned int cs,
                spi_slave->fifo_size = 256;
 
        spi_slave->skip_preamble = 0;
+       spi_slave->last_transaction_us = timer_get_us();
 
        spi_slave->freq = bus->frequency;

        if (max_hz)

drivers/spi/exynos_spi.c +0 -0

@@ -371,9 +376,21 @@ void spi_cs_activate(struct spi_slave *slave)
  {
        struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
 

drivers/spi/exynos_spi.c void spi_cs_activate(struct spi_slave *slave) · line 388

Quoted 10 lines

drivers/spi/exynos_spi.c +8 -0

+       /* If it's too soon to do another transaction, wait */
+       if (spi_slave->bus->deactivate_delay_us &&
+           spi_slave->last_transaction_us) {
+               ulong delay_us;         /* The delay completed so far */
+               delay_us = timer_get_us() -
 spi_slave->last_transaction_us;
+               if (delay_us < spi_slave->bus->deactivate_delay_us)
+                       udelay(spi_slave->bus->deactivate_delay_us -
 delay_us);
+       }

Add one space

Quoted 19 lines

drivers/spi/exynos_spi.c +2 -0

        clrbits_le32(&spi_slave->regs->cs_reg, SPI_SLAVE_SIG_INACT);
        debug("Activate CS, bus %d\n", spi_slave->slave.bus);
        spi_slave->skip_preamble = spi_slave->mode & SPI_PREAMBLE;
+
+       /* Remember time of this transaction so we can honour the bus

delay */

drivers/spi/exynos_spi.c +4 -0

+       if (spi_slave->bus->deactivate_delay_us)
+               spi_slave->last_transaction_us = timer_get_us();
  }
 
  /**

@@ -423,6 +440,8 @@ static int spi_get_config(const void *blob, int node,
 struct spi_bus *bus)
        /* Use 500KHz as a suitable default */
        bus->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
                                        500000);
+       bus->deactivate_delay_us = fdtdec_get_int(blob, node,
+                                       "spi-deactivate-delay", 0);
 

Quoted 5 lines

Quoted 3 lines

drivers/spi/exynos_spi.c +0 -0

        return 0;

  }

Was this tested, usually what is the max deactivate delay?

This was tested with 50us.

Quoted 1 line

Quoted 1 line

In this case your are passing through dts is it?

Yes that's right.

Regards,
Simon

Quoted 6 lines

Thanks,
Jagan.

Quoted 136 lines · Simon Glass

Hi Jagan,

Quoted 17 lines · Jagan Teki

Hi,

Quoted 10 lines · Rajeshwari Shinde

For devices that need some time to react after a spi transaction finishes, add the ability to set a delay.

Implement this as a delay on the first/next transaction to avoid any delay in the fairly common case where a SPI transaction is followed by other processing.

Based on:
"[U-Boot] [PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"

Quoted 8 lines

Please use the below format for referring previous commits ex:
"<PREVIOUS_COMMIT_HEAD>"
(sha1: PREVIOUS_COMMIT_ID)

in this case
"spi: exynos: Support SPI_PREAMBLE mode"
(sha1: e4eaef8910df805d511b1cb9b2caafa7d2827fdc)

I hope you don't mind me answering part of this...

Quoted 93 lines

Quoted 60 lines

Signed-off-by Simon Glass <[email protected]>

Signed-off-by Rajeshwari Shinde <[email protected]>

---
Changes in V2:
- None.
Changes in V3:
- Rebased on "[PATCH 0/2 V5] spi: Enable SPI_PREAMBLE Mode"

  drivers/spi/exynos_spi.c |   19 +++++++++++++++++++
  1 files changed, 19 insertions(+), 0 deletions(-)

drivers/spi/exynos_spi.c +1 -0

index 01378d0..03cf503 100644
@@ -38,6 +38,7 @@ struct spi_bus {
        struct exynos_spi *regs;
        int inited;             /* 1 if this bus is ready for use */
        int node;
+       uint deactivate_delay_us;       /* Delay to wait after deactivate
 */
  };
 

/* A list of spi buses that we know about */

drivers/spi/exynos_spi.c +2 -0

@@ -52,6 +53,8 @@ struct exynos_spi_slave {
        enum periph_id periph_id;       /* Peripheral ID for this device
 */
        unsigned int fifo_size;
        int skip_preamble;
+       struct spi_bus *bus;            /* Pointer to our SPI bus info */
+       ulong last_transaction_us;      /* Time of last transaction end
 */
  };

static struct spi_bus *spi_get_bus(unsigned dev_index)

drivers/spi/exynos_spi.c +1 -0

@@ -97,6 +100,7 @@ struct spi_slave *spi_setup_slave(unsigned int busnum,
 unsigned int cs,
        }
 
        bus = &spi_bus[busnum];
+       spi_slave->bus = bus;
        spi_slave->regs = bus->regs;
        spi_slave->mode = mode;

        spi_slave->periph_id = bus->periph_id;

drivers/spi/exynos_spi.c +1 -0

@@ -107,6 +111,7 @@ struct spi_slave *spi_setup_slave(unsigned int
 busnum, unsigned int cs,
                spi_slave->fifo_size = 256;
 
        spi_slave->skip_preamble = 0;
+       spi_slave->last_transaction_us = timer_get_us();
 
        spi_slave->freq = bus->frequency;

        if (max_hz)

drivers/spi/exynos_spi.c +0 -0

@@ -371,9 +376,21 @@ void spi_cs_activate(struct spi_slave *slave)
  {
        struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
 

drivers/spi/exynos_spi.c void spi_cs_activate(struct spi_slave *slave) · line 388

Quoted 10 lines

drivers/spi/exynos_spi.c +8 -0

+       /* If it's too soon to do another transaction, wait */
+       if (spi_slave->bus->deactivate_delay_us &&
+           spi_slave->last_transaction_us) {
+               ulong delay_us;         /* The delay completed so far */
+               delay_us = timer_get_us() -
 spi_slave->last_transaction_us;
+               if (delay_us < spi_slave->bus->deactivate_delay_us)
+                       udelay(spi_slave->bus->deactivate_delay_us -
 delay_us);
+       }

Add one space

Quoted 19 lines

drivers/spi/exynos_spi.c +2 -0

        clrbits_le32(&spi_slave->regs->cs_reg, SPI_SLAVE_SIG_INACT);
        debug("Activate CS, bus %d\n", spi_slave->slave.bus);
        spi_slave->skip_preamble = spi_slave->mode & SPI_PREAMBLE;
+
+       /* Remember time of this transaction so we can honour the bus

delay */

drivers/spi/exynos_spi.c +4 -0

+       if (spi_slave->bus->deactivate_delay_us)
+               spi_slave->last_transaction_us = timer_get_us();
  }
 
  /**

@@ -423,6 +440,8 @@ static int spi_get_config(const void *blob, int node,
 struct spi_bus *bus)
        /* Use 500KHz as a suitable default */
        bus->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
                                        500000);
+       bus->deactivate_delay_us = fdtdec_get_int(blob, node,
+                                       "spi-deactivate-delay", 0);
 

Quoted 5 lines

Quoted 3 lines

drivers/spi/exynos_spi.c +0 -0

        return 0;

  }

Was this tested, usually what is the max deactivate delay?

This was tested with 50us.

Quoted 1 line

Quoted 15 lines

Quoted 1 line

In this case your are passing through dts is it?

Yes that's right.

Regards,
Simon

Quoted 6 lines

Thanks,
Jagan.

Can you please send the next version patches.

--
Thanks,
Jagan.