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serial: 8250_bcm2835aux: Add ACPI support

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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.

Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Adrien Thierry <athierry@redhat.com>
Link: https://lore.kernel.org/r/20220207232129.402882-1-athierry@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Adrien Thierry 2022-02-07 18:21:29 -05:00 committed by Greg Kroah-Hartman
parent 5cfb02ced7
commit fcc446c8aa
1 changed files with 46 additions and 6 deletions
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52
drivers/tty/serial/8250/8250_bcm2835aux.c
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@ -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,