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Re: [Xen-devel] [PATCH V8 3/3] arm/acpi: Add Server Base System Architecture UART support



Hello Shanker,

On 08/06/16 14:28, Shanker Donthineni wrote:
The ARM Server Base System Architecture describes a generic UART
interface. It doesn't support clock control registers, modem
control, DMA and hardware flow control features. So, extend the
driver probe() to handle SBSA interface and skip the accessing
PL011 registers that are not described in SBSA document
(ARM-DEN-0029 Version 3.0, 6 APPENDIX B: GENERIC UART).

Signed-off-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>
Reviewed-by: Julien Grall <julien.grall@xxxxxxx>
---
Changes sicne v7:
    Moved comment 'To compatible with SBSA v2.x document, all accesses should 
be 32-bit' from #2

Changes since v3:
   Moved non-SBSA related changes to patches 1/3 and 2/3.

changes since v2:
   Edited commit text to include SBSA document version.
   Remove setting baudrate code completely as per Julien's suggestion.
   Support both the SBSA interface types ACPI_DBG2_SBSA & ACPI_DBG2_SBSA_32.
   Replace MIS references with combination of RIS & IMSC.

Changes since v1:
   Don't access UART registers that are not part of SBSA document.
   Move setting baudrate function to a separate function.

  xen/drivers/char/pl011.c | 55 +++++++++++++++++++++++++++++++++++-------------
  1 file changed, 40 insertions(+), 15 deletions(-)

diff --git a/xen/drivers/char/pl011.c b/xen/drivers/char/pl011.c
index a2f929b..d70ec99 100644
--- a/xen/drivers/char/pl011.c
+++ b/xen/drivers/char/pl011.c
@@ -41,6 +41,7 @@ static struct pl011 {
      /* struct timer timer; */
      /* unsigned int timeout_ms; */
      /* bool_t probing, intr_works; */
+    bool sbsa;  /* ARM SBSA generic interface */
  } pl011_com = {0};

  /* These parity settings can be ORed directly into the LCR. */
@@ -50,6 +51,7 @@ static struct pl011 {
  #define PARITY_MARK  (PEN|SPS)
  #define PARITY_SPACE (PEN|EPS|SPS)

+/* To compatible with SBSA v2.x document, all accesses should be 32-bit */

The verb is missing. Also please add a full stop at the end of the comment.

  #define pl011_read(uart, off)           readl((uart)->regs + (off))
  #define pl011_write(uart, off,val)      writel((val), (uart)->regs + (off))


[...]

@@ -313,11 +323,15 @@ static int __init pl011_acpi_uart_init(const void *data)
          return -EINVAL;
      }

+    if ( (spcr->interface_type == ACPI_DBG2_SBSA) ||
+         (spcr->interface_type == ACPI_DBG2_SBSA_32) )
+        sbsa = true;

I thought I already mentioned this on a previous version:

sbsa = (spcr->interface_type == ACPI_DBG2_SBSA || ...);

Regards,

--
Julien Grall

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