[U-Boot] sf: bar: Clean BA24 Bank Address Register bit after read/write/erase operation

Message ID 1505295574-14294-1-git-send-email-lukma@denx.de
State New
Delegated to: Jagannadha Sutradharudu Teki
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  • [U-Boot] sf: bar: Clean BA24 Bank Address Register bit after read/write/erase operation
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Commit Message

Łukasz Majewski Sept. 13, 2017, 9:39 a.m.
The content of Bank Address Register (BAR) is volatile. It is cleared
after power cycle or reset command (RESET F0h).

Some memories (like e.g. s25fl256s) use it to access memory larger than
0x1000000 (16 MiB).

The problem shows up when one:

1. Reads/writes/erases memory > 16 MiB
2. Calls "reset" u-boot command (which is not causing BAR to be cleared)

In the above scenario, the SoC ROM sends 0x000000 address to read SPL.
Unfortunately, the BA24 bit is still set and hence it receives content
from 0x1000000 memory address.
As a result the SoC aborts and we hang. Only power cycle can take the
SoC out of this state.

How to reproduce/test:

sf probe; sf erase 0x1200000 0x800000; reset
sf probe; sf erase 0x1200000 0x800000; sf write 0x11000000 0x1200000 0x800000; reset
sf probe; sf read 0x11000000 0x1200000 0x800000; reset

Signed-off-by: Lukasz Majewski <lukma@denx.de>
---
 drivers/mtd/spi/spi_flash.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

Comments

Fabio Estevam Sept. 13, 2017, 4:02 p.m. | #1
Hi Lukasz,

On Wed, Sep 13, 2017 at 6:39 AM, Lukasz Majewski <lukma@denx.de> wrote:

>  #ifdef CONFIG_SPI_FLASH_BAR
> +/*
> + * This "cleanup" is necessary in a situation when one was accessing
> + * spi flash memory > 16 MiB by using Bank Address Register's BA24 bit.
> + *
> + * After it the BA24 bit shall be cleared to allow access to correct
> + * memory region after SW reset (by calling "reset" command).
> + *
> + * Otherwise, the BA24 bit may be left set and then after reset, the
> + * ROM would seek for SPL from 0x1000000, not 0x0.
> + */
> +static int cleanup_bar(struct spi_flash *flash)
> +{
> +       u8 cmd, bank_sel = 0;
> +
> +       if (flash->bank_curr == 0)
> +               return 0;
> +       cmd = flash->bank_write_cmd;
> +
> +       return spi_flash_write_common(flash, &cmd, 1, &bank_sel, 1);
> +}
> +

What about defining an empty stub for this function when
CONFIG_SPI_FLASH_BAR is not defined?

>  static int write_bar(struct spi_flash *flash, u32 offset)
>  {
>         u8 cmd, bank_sel;
> @@ -339,6 +360,10 @@ int spi_flash_cmd_erase_ops(struct spi_flash *flash, u32 offset, size_t len)
>                 len -= erase_size;
>         }
>
> +#ifdef CONFIG_SPI_FLASH_BAR
> +       ret = cleanup_bar(flash);
> +#endif

Then you don't need to add the ifdefs when calling cleanup_bar().
Łukasz Majewski Sept. 13, 2017, 4:06 p.m. | #2
Hi Fabio,

> Hi Lukasz,
> 
> On Wed, Sep 13, 2017 at 6:39 AM, Lukasz Majewski <lukma@denx.de> wrote:
> 
>>   #ifdef CONFIG_SPI_FLASH_BAR
>> +/*
>> + * This "cleanup" is necessary in a situation when one was accessing
>> + * spi flash memory > 16 MiB by using Bank Address Register's BA24 bit.
>> + *
>> + * After it the BA24 bit shall be cleared to allow access to correct
>> + * memory region after SW reset (by calling "reset" command).
>> + *
>> + * Otherwise, the BA24 bit may be left set and then after reset, the
>> + * ROM would seek for SPL from 0x1000000, not 0x0.
>> + */
>> +static int cleanup_bar(struct spi_flash *flash)
>> +{
>> +       u8 cmd, bank_sel = 0;
>> +
>> +       if (flash->bank_curr == 0)
>> +               return 0;
>> +       cmd = flash->bank_write_cmd;
>> +
>> +       return spi_flash_write_common(flash, &cmd, 1, &bank_sel, 1);
>> +}
>> +
> 
> What about defining an empty stub for this function when
> CONFIG_SPI_FLASH_BAR is not defined?
> 
>>   static int write_bar(struct spi_flash *flash, u32 offset)
>>   {
>>          u8 cmd, bank_sel;
>> @@ -339,6 +360,10 @@ int spi_flash_cmd_erase_ops(struct spi_flash *flash, u32 offset, size_t len)
>>                  len -= erase_size;
>>          }
>>
>> +#ifdef CONFIG_SPI_FLASH_BAR
>> +       ret = cleanup_bar(flash);
>> +#endif
> 
> Then you don't need to add the ifdefs when calling cleanup_bar().

I took the approach already used in this file, so I would prefer to 
leave it is in this patch (to be in sync with the rest).

>

Patch

diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index 34f6888..d19d64a 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -113,6 +113,27 @@  static int write_cr(struct spi_flash *flash, u8 wc)
 #endif
 
 #ifdef CONFIG_SPI_FLASH_BAR
+/*
+ * This "cleanup" is necessary in a situation when one was accessing
+ * spi flash memory > 16 MiB by using Bank Address Register's BA24 bit.
+ *
+ * After it the BA24 bit shall be cleared to allow access to correct
+ * memory region after SW reset (by calling "reset" command).
+ *
+ * Otherwise, the BA24 bit may be left set and then after reset, the
+ * ROM would seek for SPL from 0x1000000, not 0x0.
+ */
+static int cleanup_bar(struct spi_flash *flash)
+{
+	u8 cmd, bank_sel = 0;
+
+	if (flash->bank_curr == 0)
+		return 0;
+	cmd = flash->bank_write_cmd;
+
+	return spi_flash_write_common(flash, &cmd, 1, &bank_sel, 1);
+}
+
 static int write_bar(struct spi_flash *flash, u32 offset)
 {
 	u8 cmd, bank_sel;
@@ -339,6 +360,10 @@  int spi_flash_cmd_erase_ops(struct spi_flash *flash, u32 offset, size_t len)
 		len -= erase_size;
 	}
 
+#ifdef CONFIG_SPI_FLASH_BAR
+	ret = cleanup_bar(flash);
+#endif
+
 	return ret;
 }
 
@@ -397,6 +422,10 @@  int spi_flash_cmd_write_ops(struct spi_flash *flash, u32 offset,
 		offset += chunk_len;
 	}
 
+#ifdef CONFIG_SPI_FLASH_BAR
+	ret = cleanup_bar(flash);
+#endif
+
 	return ret;
 }
 
@@ -500,6 +529,10 @@  int spi_flash_cmd_read_ops(struct spi_flash *flash, u32 offset,
 		data += read_len;
 	}
 
+#ifdef CONFIG_SPI_FLASH_BAR
+	ret = cleanup_bar(flash);
+#endif
+
 	free(cmd);
 	return ret;
 }