Serial Flash: call spi_flash_free more coherently

The release command is the pendant of the probe command. This command allows to call spi_flash_free from the command line. This may be necessary for some boards where sf probe does change the state of the hardware (like with some pin multiplexing changes for instance).

Signed-off-by Valentin Longchamp <[email protected]>

---

Changes in v3:
- Rebased on v2015.10

Changes in v2:
- Rebased on v2014.10

 common/cmd_sf.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

common/cmd_sf.c +11 -1

index ac7f5df..9c51dca 100644
@@ -152,6 +152,14 @@ static int do_spi_flash_probe(int argc, char * const argv[])
        return 0;
 }
 
+static int do_spi_flash_release(int argc, char * const argv[])
+{
+       if (flash)
+               spi_flash_free(flash);
+       flash = NULL;
+
+       return 0;
+}
 /**
  * Write a block of data to SPI flash, first checking if it is different from
  * what is already there.

@@ -540,6 +548,8 @@ static int do_spi_flash(cmd_tbl_t *cmdtp, int flag, int argc,
                ret = do_spi_flash_read_write(argc, argv);
        else if (strcmp(cmd, "erase") == 0)
                ret = do_spi_flash_erase(argc, argv);
+       else if (strcmp(cmd, "release") == 0)
+               ret = do_spi_flash_release(argc, argv);
 #ifdef CONFIG_CMD_SF_TEST
        else if (!strcmp(cmd, "test"))
                ret = do_spi_flash_test(argc, argv);

@@ -579,5 +589,6 @@ U_BOOT_CMD(
        "sf update addr offset|partition len    - erase and write `len' bytes from memory\n"
        "                                         at `addr' to flash at `offset'\n"
        "                                         or to start of mtd `partition'\n"
+       "sf release                             - release the current flash device\n"
        SF_TEST_HELP
 );
--

1.8.3.1

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Quoted 4 lines · Valentin Longchamp

The release command is the pendant of the probe command. This command allows to call spi_flash_free from the command line. This may be necessary for some boards where sf probe does change the state of the hardware (like with some pin multiplexing changes for instance).

So you want to change the state of pin multiplexing on your board with connected slave devices example: spi nor flash is it? what exactly the need of releasing? why can't we use pin multiplexing changes like selecting or deselecting particular lines through driver or from board files itself.

Quoted 56 lines

Signed-off-by Valentin Longchamp <[email protected]>

---

Changes in v3:
- Rebased on v2015.10

Changes in v2:
- Rebased on v2014.10

 common/cmd_sf.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

common/cmd_sf.c +11 -1

index ac7f5df..9c51dca 100644
@@ -152,6 +152,14 @@ static int do_spi_flash_probe(int argc, char * const argv[])
        return 0;
 }
 
+static int do_spi_flash_release(int argc, char * const argv[])
+{
+       if (flash)
+               spi_flash_free(flash);
+       flash = NULL;
+
+       return 0;
+}
 /**
  * Write a block of data to SPI flash, first checking if it is different from
  * what is already there.

@@ -540,6 +548,8 @@ static int do_spi_flash(cmd_tbl_t *cmdtp, int flag, int argc,
                ret = do_spi_flash_read_write(argc, argv);
        else if (strcmp(cmd, "erase") == 0)
                ret = do_spi_flash_erase(argc, argv);
+       else if (strcmp(cmd, "release") == 0)
+               ret = do_spi_flash_release(argc, argv);
 #ifdef CONFIG_CMD_SF_TEST
        else if (!strcmp(cmd, "test"))
                ret = do_spi_flash_test(argc, argv);

@@ -579,5 +589,6 @@ U_BOOT_CMD(
        "sf update addr offset|partition len    - erase and write `len' bytes from memory\n"
        "                                         at `addr' to flash at `offset'\n"
        "                                         or to start of mtd `partition'\n"
+       "sf release                             - release the current flash device\n"
        SF_TEST_HELP
 );
--

1.8.3.1

_______________________________________________
U-Boot mailing list
U-Boot at lists.denx.de
http://lists.denx.de/mailman/listinfo/u-boot

Quoted 7 lines · Jagan Teki

Quoted 4 lines · Valentin Longchamp

The release command is the pendant of the probe command. This command allows to call spi_flash_free from the command line. This may be necessary for some boards where sf probe does change the state of the hardware (like with some pin multiplexing changes for instance).

Quoted 5 lines

So you want to change the state of pin multiplexing on your board with connected slave devices example: spi nor flash is it? what exactly the need of releasing? why can't we use pin multiplexing changes like selecting or deselecting particular lines through driver or from board files itself.

That's our use case yes. Let me explain you it again in detail. Some of the signals used to access the NAND Flash and the SPI NOR are shared. At reset, they are available for the SPI NOR, since u-boot is in there and the CPU then accesses it.

In an usual boot sequence, the SPI NOR is accessed first (copying u-boot to the RAM, reading out the environment) and so the pins are configured in hardware at boot time for accessing the SPI NOR. After that, they are configured to access the NAND where the kernel and filesystem are stored to boot Linux thanks to env_relocate_spec() calling spi_flash_free() on exit in conjunction with [1]

Now in the case where the boot sequence is interrupted and some accesses are done to the SPI NOR, the pins are changed again to SPI NOR to perform these accesses. But we have to make sure that the pins are configured back to NAND by calling spi_flash_free() after these accesses and that's why I introduced the release() function.

In our case, there are 2 types of such accesses:
- environment variables write: this is the first patch of the series. It simply adds calls to spi_flash_free() at function exit no only in env_relocate_spec() but also in saveenv() so that the behavior here is coherent for the whole env_sf file (spi_flash_probe() at function start, spi_flash_free() at function exit).
- updating u-boot: this is solved for us with the last 2 patches of the series. The first one just adds a sf release command that does the opposite/cleanup to sf probe and the second patch just calls this command in our scripts where u-boot is updated/the SPI NOR is written.

We are *indeed* using pin multiplexing changes, in our case, they are implemented in the spi controller driver: drivers/spi/kirkwood_spi.c. To be very specific, in our case this sf release command allows to explicitely call spi_flash_free() which calls spi_free_slave(), which in our case (kirkwood_spi.c) sets the pins back to their previous configuration.

Hi,

Quoted 41 lines · Valentin Longchamp

Quoted 7 lines · Jagan Teki

Quoted 4 lines · Valentin Longchamp

The release command is the pendant of the probe command. This command allows to call spi_flash_free from the command line. This may be necessary for some boards where sf probe does change the state of the hardware (like with some pin multiplexing changes for instance).

Quoted 5 lines

So you want to change the state of pin multiplexing on your board with connected slave devices example: spi nor flash is it? what exactly the need of releasing? why can't we use pin multiplexing changes like selecting or deselecting particular lines through driver or from board files itself.

That's our use case yes. Let me explain you it again in detail. Some of the signals used to access the NAND Flash and the SPI NOR are shared. At reset, they are available for the SPI NOR, since u-boot is in there and the CPU then accesses it.

In an usual boot sequence, the SPI NOR is accessed first (copying u-boot to the RAM, reading out the environment) and so the pins are configured in hardware at boot time for accessing the SPI NOR. After that, they are configured to access the NAND where the kernel and filesystem are stored to boot Linux thanks to env_relocate_spec() calling spi_flash_free() on exit in conjunction with [1]

Now in the case where the boot sequence is interrupted and some accesses are done to the SPI NOR, the pins are changed again to SPI NOR to perform these accesses. But we have to make sure that the pins are configured back to NAND by calling spi_flash_free() after these accesses and that's why I introduced the release() function.

In our case, there are 2 types of such accesses:
- environment variables write: this is the first patch of the series. It simply adds calls to spi_flash_free() at function exit no only in env_relocate_spec() but also in saveenv() so that the behavior here is coherent for the whole env_sf file (spi_flash_probe() at function start, spi_flash_free() at function exit).
- updating u-boot: this is solved for us with the last 2 patches of the series. The first one just adds a sf release command that does the opposite/cleanup to sf probe and the second patch just calls this command in our scripts where u-boot is updated/the SPI NOR is written.

Quoted 5 lines

We are *indeed* using pin multiplexing changes, in our case, they are implemented in the spi controller driver: drivers/spi/kirkwood_spi.c. To be very specific, in our case this sf release command allows to explicitely call spi_flash_free() which calls spi_free_slave(), which in our case (kirkwood_spi.c) sets the pins back to their previous configuration.

Does your board use driver model from SPI and SPI flash? If not I think that should be the first step.

Hi Simon,

Quoted 45 lines · Simon Glass

Hi,

Quoted 41 lines · Valentin Longchamp

Quoted 7 lines · Jagan Teki

Quoted 4 lines · Valentin Longchamp

The release command is the pendant of the probe command. This command allows to call spi_flash_free from the command line. This may be necessary for some boards where sf probe does change the state of the hardware (like with some pin multiplexing changes for instance).

Quoted 5 lines

So you want to change the state of pin multiplexing on your board with connected slave devices example: spi nor flash is it? what exactly the need of releasing? why can't we use pin multiplexing changes like selecting or deselecting particular lines through driver or from board files itself.

That's our use case yes. Let me explain you it again in detail. Some of the signals used to access the NAND Flash and the SPI NOR are shared. At reset, they are available for the SPI NOR, since u-boot is in there and the CPU then accesses it.

In an usual boot sequence, the SPI NOR is accessed first (copying u-boot to the RAM, reading out the environment) and so the pins are configured in hardware at boot time for accessing the SPI NOR. After that, they are configured to access the NAND where the kernel and filesystem are stored to boot Linux thanks to env_relocate_spec() calling spi_flash_free() on exit in conjunction with [1]

Now in the case where the boot sequence is interrupted and some accesses are done to the SPI NOR, the pins are changed again to SPI NOR to perform these accesses. But we have to make sure that the pins are configured back to NAND by calling spi_flash_free() after these accesses and that's why I introduced the release() function.

In our case, there are 2 types of such accesses:
- environment variables write: this is the first patch of the series. It simply adds calls to spi_flash_free() at function exit no only in env_relocate_spec() but also in saveenv() so that the behavior here is coherent for the whole env_sf file (spi_flash_probe() at function start, spi_flash_free() at function exit).
- updating u-boot: this is solved for us with the last 2 patches of the series. The first one just adds a sf release command that does the opposite/cleanup to sf probe and the second patch just calls this command in our scripts where u-boot is updated/the SPI NOR is written.

Quoted 9 lines

Quoted 5 lines

We are *indeed* using pin multiplexing changes, in our case, they are implemented in the spi controller driver: drivers/spi/kirkwood_spi.c. To be very specific, in our case this sf release command allows to explicitely call spi_flash_free() which calls spi_free_slave(), which in our case (kirkwood_spi.c) sets the pins back to their previous configuration.

Does your board use driver model from SPI and SPI flash? If not I think that should be the first step.

No we don't. Could you please elaborate on how this would cover this use case and should be the first step ?

I am open to other ways to cover this use case of ours, especially since this was done more than 2 years ago and u-boot has changed since then. However I don't see the direct link between the driver model and how it would allow to make sure spi_flash_free() is called in our u-boot env scripts.

Hi Valentine,

Quoted 61 lines · Valentin Longchamp

Hi Simon,

Quoted 45 lines · Simon Glass

Hi,

Quoted 41 lines · Valentin Longchamp

Quoted 7 lines · Jagan Teki

Quoted 4 lines · Valentin Longchamp

The release command is the pendant of the probe command. This command allows to call spi_flash_free from the command line. This may be necessary for some boards where sf probe does change the state of the hardware (like with some pin multiplexing changes for instance).

Quoted 5 lines

So you want to change the state of pin multiplexing on your board with connected slave devices example: spi nor flash is it? what exactly the need of releasing? why can't we use pin multiplexing changes like selecting or deselecting particular lines through driver or from board files itself.

That's our use case yes. Let me explain you it again in detail. Some of the signals used to access the NAND Flash and the SPI NOR are shared. At reset, they are available for the SPI NOR, since u-boot is in there and the CPU then accesses it.

In an usual boot sequence, the SPI NOR is accessed first (copying u-boot to the RAM, reading out the environment) and so the pins are configured in hardware at boot time for accessing the SPI NOR. After that, they are configured to access the NAND where the kernel and filesystem are stored to boot Linux thanks to env_relocate_spec() calling spi_flash_free() on exit in conjunction with [1]

Now in the case where the boot sequence is interrupted and some accesses are done to the SPI NOR, the pins are changed again to SPI NOR to perform these accesses. But we have to make sure that the pins are configured back to NAND by calling spi_flash_free() after these accesses and that's why I introduced the release() function.

In our case, there are 2 types of such accesses:
- environment variables write: this is the first patch of the series. It simply adds calls to spi_flash_free() at function exit no only in env_relocate_spec() but also in saveenv() so that the behavior here is coherent for the whole env_sf file (spi_flash_probe() at function start, spi_flash_free() at function exit).
- updating u-boot: this is solved for us with the last 2 patches of the series. The first one just adds a sf release command that does the opposite/cleanup to sf probe and the second patch just calls this command in our scripts where u-boot is updated/the SPI NOR is written.

Quoted 9 lines

Quoted 5 lines

We are *indeed* using pin multiplexing changes, in our case, they are implemented in the spi controller driver: drivers/spi/kirkwood_spi.c. To be very specific, in our case this sf release command allows to explicitely call spi_flash_free() which calls spi_free_slave(), which in our case (kirkwood_spi.c) sets the pins back to their previous configuration.

Does your board use driver model from SPI and SPI flash? If not I think that should be the first step.

No we don't. Could you please elaborate on how this would cover this use case and should be the first step ?

Quoted 4 lines

I am open to other ways to cover this use case of ours, especially since this was done more than 2 years ago and u-boot has changed since then. However I don't see the direct link between the driver model and how it would allow to make sure spi_flash_free() is called in our u-boot env scripts.

In driver model you would have a remove() method for your SPI driver which does the required pinmux changing.

There is a detailed howto in doc/driver-model showing how to port your driver over. Please let me know if you need any help/ideas.

Quoted 7 lines

Quoted 7 lines

Quoted 3 lines

Does your board use driver model from SPI and SPI flash? If not I think that should be the first step.

No we don't. Could you please elaborate on how this would cover this use case and should be the first step ?

Quoted 7 lines

Quoted 4 lines

I am open to other ways to cover this use case of ours, especially since this was done more than 2 years ago and u-boot has changed since then. However I don't see the direct link between the driver model and how it would allow to make sure spi_flash_free() is called in our u-boot env scripts.

In driver model you would have a remove() method for your SPI driver which does the required pinmux changing.

OK, when looking at SPI flash, SPI controller driver and the driver model, I have found out why we require this "release" command.

So the SPI subsystem and its drivers (with or without DM support) make sure that spi_claim_bus/release_bus are called before/after the accesses. This should cover the pinmux configuration stuff.

In our case, it was not sufficient since drivers/spi/kirkwood_spi.c does the pinmux configuration at 2 places: spi_claim_bus/release_bus for the IO (MOSI/MISO/CLK) AND spi_setup_slave/free_slave for the chip select.

Since spi_free_slave is not always called after spi_setup_slave (for instance after a sf probe command on the u-boot prompt), the CS pin was not always given back to the NAND flash controller that's why there was a need for a sf release command in our case.

I have now moved all the pinmux configuration for kirkwood_spi into spi_claim_bus/release_bus and the need for this sf release command is not necessary anymore.

I am going to test this a bit more and send a new patch series which will not require this release command.

Quoted 1 line

Quoted 2 lines

There is a detailed howto in doc/driver-model showing how to port your driver over. Please let me know if you need any help/ideas.

I have had a look at it and it is a great help on porting a driver to this model. That's something we plan to do for our boards eventually.

Hi Valentine,

On 24.11.2015 17:02, Valentin Longchamp wrote:

<snip>

Quoted 42 lines

Quoted 7 lines

Quoted 7 lines

Quoted 3 lines

Does your board use driver model from SPI and SPI flash? If not I think that should be the first step.

No we don't. Could you please elaborate on how this would cover this use case and should be the first step ?

Quoted 7 lines

Quoted 4 lines

I am open to other ways to cover this use case of ours, especially since this was done more than 2 years ago and u-boot has changed since then. However I don't see the direct link between the driver model and how it would allow to make sure spi_flash_free() is called in our u-boot env scripts.

In driver model you would have a remove() method for your SPI driver which does the required pinmux changing.

OK, when looking at SPI flash, SPI controller driver and the driver model, I have found out why we require this "release" command.

So the SPI subsystem and its drivers (with or without DM support) make sure that spi_claim_bus/release_bus are called before/after the accesses. This should cover the pinmux configuration stuff.

In our case, it was not sufficient since drivers/spi/kirkwood_spi.c does the pinmux configuration at 2 places: spi_claim_bus/release_bus for the IO (MOSI/MISO/CLK) AND spi_setup_slave/free_slave for the chip select.

Since spi_free_slave is not always called after spi_setup_slave (for instance after a sf probe command on the u-boot prompt), the CS pin was not always given back to the NAND flash controller that's why there was a need for a sf release command in our case.

I have now moved all the pinmux configuration for kirkwood_spi into spi_claim_bus/release_bus and the need for this sf release command is not necessary anymore.

I am going to test this a bit more and send a new patch series which will not require this release command.

Quoted 3 lines

There is a detailed howto in doc/driver-model showing how to port your driver over. Please let me know if you need any help/ideas.

Quoted 2 lines

I have had a look at it and it is a great help on porting a driver to this model. That's something we plan to do for our boards eventually.

So did you already port the kirkwood SPI driver to DM? I'm asking, since I also do have a patch for this in the queue. I'll hopefully be able to post it by end of this week.

BTW: I would love to see the Kirkwood platform to be moved over to arch-mvebu at some time, which already supports DM.