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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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