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Message-Id: <20220207232129.402882-1-athierry@redhat.com> Date: Mon, 7 Feb 2022 18:21:29 -0500 From: Adrien Thierry <athierry@...hat.com> To: linux-serial@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Cc: Adrien Thierry <athierry@...hat.com>, Jeremy Linton <jeremy.linton@....com>, 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: [PATCH v3] serial: 8250_bcm2835aux: Add ACPI support 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. 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 -- 2.34.1
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