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Message-ID: <827f3c8b-b89a-018f-a5af-3984c7bc8492@arm.com>
Date: Tue, 8 Feb 2022 01:18:09 -0600
From: Jeremy Linton <jeremy.linton@....com>
To: Adrien Thierry <athierry@...hat.com>, linux-serial@...r.kernel.org,
linux-rpi-kernel@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>,
Nicolas Saenz Julienne <nsaenz@...nel.org>,
Florian Fainelli <f.fainelli@...il.com>,
Ray Jui <rjui@...adcom.com>,
Scott Branden <sbranden@...adcom.com>,
bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH v3] serial: 8250_bcm2835aux: Add ACPI support
Hi,
On 2/7/22 17:21, Adrien Thierry wrote:
> Add ACPI support to 8250_bcm2835aux driver. This makes it possible to
> use the miniuart on the Raspberry Pi with the tianocore/edk2 UEFI
> firmware.
I merged this to 5.17rc3, switched the console to this device and it now
works in linux! Thanks for doing this!
Tested-by: Jeremy Linton <jeremy.linton@....com>
>
> Signed-off-by: Adrien Thierry <athierry@...hat.com>
> ---
> V1 -> V2: Refactored code to remove unnecessary conditional paths and
> intermediate variables
> V2 -> V3: Cleaned up coding style and addressed review comments
>
> drivers/tty/serial/8250/8250_bcm2835aux.c | 52 ++++++++++++++++++++---
> 1 file changed, 46 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_bcm2835aux.c b/drivers/tty/serial/8250/8250_bcm2835aux.c
> index fd95860cd661..2a1226a78a0c 100644
> --- a/drivers/tty/serial/8250/8250_bcm2835aux.c
> +++ b/drivers/tty/serial/8250/8250_bcm2835aux.c
> @@ -17,6 +17,7 @@
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/platform_device.h>
> +#include <linux/property.h>
>
> #include "8250.h"
>
> @@ -44,6 +45,10 @@ struct bcm2835aux_data {
> u32 cntl;
> };
>
> +struct bcm2835_aux_serial_driver_data {
> + resource_size_t offset;
> +};
> +
> static void bcm2835aux_rs485_start_tx(struct uart_8250_port *up)
> {
> if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
> @@ -80,9 +85,12 @@ static void bcm2835aux_rs485_stop_tx(struct uart_8250_port *up)
>
> static int bcm2835aux_serial_probe(struct platform_device *pdev)
> {
> + const struct bcm2835_aux_serial_driver_data *bcm_data;
> struct uart_8250_port up = { };
> struct bcm2835aux_data *data;
> + resource_size_t offset = 0;
> struct resource *res;
> + unsigned int uartclk;
> int ret;
>
> /* allocate the custom structure */
> @@ -109,9 +117,7 @@ static int bcm2835aux_serial_probe(struct platform_device *pdev)
> platform_set_drvdata(pdev, data);
>
> /* get the clock - this also enables the HW */
> - data->clk = devm_clk_get(&pdev->dev, NULL);
> - if (IS_ERR(data->clk))
> - return dev_err_probe(&pdev->dev, PTR_ERR(data->clk), "could not get clk\n");
> + data->clk = devm_clk_get_optional(&pdev->dev, NULL);
>
> /* get the interrupt */
> ret = platform_get_irq(pdev, 0);
> @@ -125,8 +131,24 @@ static int bcm2835aux_serial_probe(struct platform_device *pdev)
> dev_err(&pdev->dev, "memory resource not found");
> return -EINVAL;
> }
> - up.port.mapbase = res->start;
> - up.port.mapsize = resource_size(res);
> +
> + bcm_data = device_get_match_data(&pdev->dev);
> +
> + /* Some UEFI implementations (e.g. tianocore/edk2 for the Raspberry Pi)
> + * describe the miniuart with a base address that encompasses the auxiliary
> + * registers shared between the miniuart and spi.
> + *
> + * This is due to historical reasons, see discussion here :
> + * https://edk2.groups.io/g/devel/topic/87501357#84349
> + *
> + * We need to add the offset between the miniuart and auxiliary
> + * registers to get the real miniuart base address.
> + */
> + if (bcm_data)
> + offset = bcm_data->offset;
> +
> + up.port.mapbase = res->start + offset;
> + up.port.mapsize = resource_size(res) - offset;
>
> /* Check for a fixed line number */
> ret = of_alias_get_id(pdev->dev.of_node, "serial");
> @@ -141,12 +163,19 @@ static int bcm2835aux_serial_probe(struct platform_device *pdev)
> return ret;
> }
>
> + uartclk = clk_get_rate(data->clk);
> + if (!uartclk) {
> + ret = device_property_read_u32(&pdev->dev, "clock-frequency", &uartclk);
> + if (ret)
> + return dev_err_probe(&pdev->dev, ret, "could not get clk rate\n");
> + }
> +
> /* the HW-clock divider for bcm2835aux is 8,
> * but 8250 expects a divider of 16,
> * so we have to multiply the actual clock by 2
> * to get identical baudrates.
> */
> - up.port.uartclk = clk_get_rate(data->clk) * 2;
> + up.port.uartclk = uartclk * 2;
>
> /* register the port */
> ret = serial8250_register_8250_port(&up);
> @@ -173,16 +202,27 @@ static int bcm2835aux_serial_remove(struct platform_device *pdev)
> return 0;
> }
>
> +static const struct bcm2835_aux_serial_driver_data bcm2835_acpi_data = {
> + .offset = 0x40,
> +};
> +
> static const struct of_device_id bcm2835aux_serial_match[] = {
> { .compatible = "brcm,bcm2835-aux-uart" },
> { },
> };
> MODULE_DEVICE_TABLE(of, bcm2835aux_serial_match);
>
> +static const struct acpi_device_id bcm2835aux_serial_acpi_match[] = {
> + { "BCM2836", (kernel_ulong_t)&bcm2835_acpi_data },
> + { }
> +};
> +MODULE_DEVICE_TABLE(acpi, bcm2835aux_serial_acpi_match);
> +
> static struct platform_driver bcm2835aux_serial_driver = {
> .driver = {
> .name = "bcm2835-aux-uart",
> .of_match_table = bcm2835aux_serial_match,
> + .acpi_match_table = bcm2835aux_serial_acpi_match,
> },
> .probe = bcm2835aux_serial_probe,
> .remove = bcm2835aux_serial_remove,
>
> base-commit: 2ade8eef993c37a2a43e51a9b1f6c25509a2acce
>
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