From: Stefano Stabellini <sstabellini@kernel.org>
To: Michal Orzel <michal.orzel@amd.com>
Cc: xen-devel@lists.xenproject.org,
Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien@xen.org>,
Bertrand Marquis <bertrand.marquis@arm.com>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: [PATCH 1/4] xen/arm: debug-pl011: Use correct accessors
Date: Wed, 14 Jun 2023 18:36:37 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2306141836050.897208@ubuntu-linux-20-04-desktop> (raw)
In-Reply-To: <20230607092727.19654-2-michal.orzel@amd.com>
On Wed, 7 Jun 2023, Michal Orzel wrote:
> Although most PL011 UARTs can cope with 32-bit accesses, some of the old
> legacy ones might not. PL011 registers are 8/16-bit wide and this shall
> be perceived as the normal behavior.
>
> Modify early printk pl011 code for arm32/arm64 to use the correct
> accessors depending on the register size (refer ARM DDI 0183G, Table 3.1).
>
> Signed-off-by: Michal Orzel <michal.orzel@amd.com>
> ---
> Next patch will override strX,ldrX with macros but I prefer to keep the
> history clean (+ possibiltity for a backport if needed).
> ---
> xen/arch/arm/arm32/debug-pl011.inc | 12 ++++++------
> xen/arch/arm/arm64/debug-pl011.inc | 6 +++---
> 2 files changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/xen/arch/arm/arm32/debug-pl011.inc b/xen/arch/arm/arm32/debug-pl011.inc
> index c527f1d4424d..9fe0c2503831 100644
> --- a/xen/arch/arm/arm32/debug-pl011.inc
> +++ b/xen/arch/arm/arm32/debug-pl011.inc
> @@ -26,13 +26,13 @@
> */
> .macro early_uart_init rb, rc, rd
> mov \rc, #(7372800 / CONFIG_EARLY_UART_PL011_BAUD_RATE % 16)
> - str \rc, [\rb, #FBRD] /* -> UARTFBRD (Baud divisor fraction) */
> + strb \rc, [\rb, #FBRD] /* -> UARTFBRD (Baud divisor fraction) */
> mov \rc, #(7372800 / CONFIG_EARLY_UART_PL011_BAUD_RATE / 16)
> - str \rc, [\rb, #IBRD] /* -> UARTIBRD (Baud divisor integer) */
> + strh \rc, [\rb, #IBRD] /* -> UARTIBRD (Baud divisor integer) */
> mov \rc, #WLEN_8 /* 8n1 */
> - str \rc, [\rb, #LCR_H] /* -> UARTLCR_H (Line control) */
> + strb \rc, [\rb, #LCR_H] /* -> UARTLCR_H (Line control) */
> ldr \rc, =(RXE | TXE | UARTEN) /* RXE | TXE | UARTEN */
> - str \rc, [\rb, #CR] /* -> UARTCR (Control Register) */
> + strh \rc, [\rb, #CR] /* -> UARTCR (Control Register) */
> .endm
>
> /*
> @@ -42,7 +42,7 @@
> */
> .macro early_uart_ready rb, rc
> 1:
> - ldr \rc, [\rb, #FR] /* <- UARTFR (Flag register) */
> + ldrh \rc, [\rb, #FR] /* <- UARTFR (Flag register) */
> tst \rc, #BUSY /* Check BUSY bit */
> bne 1b /* Wait for the UART to be ready */
> .endm
> @@ -53,7 +53,7 @@
> * rt: register which contains the character to transmit
> */
> .macro early_uart_transmit rb, rt
> - str \rt, [\rb, #DR] /* -> UARTDR (Data Register) */
> + strb \rt, [\rb, #DR] /* -> UARTDR (Data Register) */
Isn't UARTDR potentially 12-bit? I am not sure if we should use strb or
strh here...
Everything else checks out.
> .endm
>
> /*
> diff --git a/xen/arch/arm/arm64/debug-pl011.inc b/xen/arch/arm/arm64/debug-pl011.inc
> index 6d60e78c8ba3..df713eff4922 100644
> --- a/xen/arch/arm/arm64/debug-pl011.inc
> +++ b/xen/arch/arm/arm64/debug-pl011.inc
> @@ -25,13 +25,13 @@
> */
> .macro early_uart_init xb, c
> mov x\c, #(7372800 / CONFIG_EARLY_UART_PL011_BAUD_RATE % 16)
> - strh w\c, [\xb, #FBRD] /* -> UARTFBRD (Baud divisor fraction) */
> + strb w\c, [\xb, #FBRD] /* -> UARTFBRD (Baud divisor fraction) */
> mov x\c, #(7372800 / CONFIG_EARLY_UART_PL011_BAUD_RATE / 16)
> strh w\c, [\xb, #IBRD] /* -> UARTIBRD (Baud divisor integer) */
> mov x\c, #WLEN_8 /* 8n1 */
> - str w\c, [\xb, #LCR_H] /* -> UARTLCR_H (Line control) */
> + strb w\c, [\xb, #LCR_H] /* -> UARTLCR_H (Line control) */
> ldr x\c, =(RXE | TXE | UARTEN)
> - str w\c, [\xb, #CR] /* -> UARTCR (Control Register) */
> + strh w\c, [\xb, #CR] /* -> UARTCR (Control Register) */
> .endm
>
> /*
> --
> 2.25.1
>
next prev parent reply other threads:[~2023-06-15 1:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-07 9:27 [PATCH 0/4] xen/arm: pl011: Use correct accessors Michal Orzel
2023-06-07 9:27 ` [PATCH 1/4] xen/arm: debug-pl011: " Michal Orzel
2023-06-13 2:59 ` Henry Wang
2023-06-15 1:36 ` Stefano Stabellini [this message]
2023-06-15 6:41 ` Michal Orzel
2023-06-15 21:03 ` Stefano Stabellini
2023-06-07 9:27 ` [PATCH 2/4] xen/arm: debug-pl011: Add support for 32-bit only MMIO Michal Orzel
2023-06-13 2:59 ` Henry Wang
2023-06-15 1:42 ` Stefano Stabellini
2023-06-07 9:27 ` [PATCH 3/4] xen/arm: pl011: Use correct accessors Michal Orzel
2023-06-13 2:59 ` Henry Wang
2023-06-15 1:49 ` Stefano Stabellini
2023-06-07 9:27 ` [PATCH 4/4] xen/arm: pl011: Add SBSA UART device-tree support Michal Orzel
2023-06-13 3:00 ` Henry Wang
2023-06-15 1:50 ` Stefano Stabellini
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