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@xxxxxxxxxx>
---
drivers/tty/serial/8250/8250_bcm2835aux.c | 103 +++++++++++++++++-----
1 file changed, 83 insertions(+), 20 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_bcm2835aux.c
b/drivers/tty/serial/8250/8250_bcm2835aux.c
index fd95860cd..b904b321e 100644
--- a/drivers/tty/serial/8250/8250_bcm2835aux.c
+++ b/drivers/tty/serial/8250/8250_bcm2835aux.c
@@ -12,6 +12,7 @@
* simultaneously to rs485.
*/
+#include <linux/acpi.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/module.h>
@@ -44,6 +45,10 @@ struct bcm2835aux_data {
u32 cntl;
};
+struct bcm2835_aux_serial_acpi_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)) {
@@ -82,8 +87,12 @@ static int bcm2835aux_serial_probe(struct
platform_device *pdev)
{
struct uart_8250_port up = { };
struct bcm2835aux_data *data;
+ struct bcm2835_aux_serial_acpi_driver_data *acpi_data;
struct resource *res;
int ret;
+ resource_size_t mapbase;
+ resource_size_t mapsize;
+ unsigned int uartclk;
/* allocate the custom structure */
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
@@ -108,10 +117,12 @@ 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");
+ if (dev_of_node(&pdev->dev)) {
+ /* 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");
+ }
/* get the interrupt */
ret = platform_get_irq(pdev, 0);
@@ -125,20 +136,59 @@ 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);
-
- /* Check for a fixed line number */
- ret = of_alias_get_id(pdev->dev.of_node, "serial");
- if (ret >= 0)
- up.port.line = ret;
-
- /* enable the clock as a last step */
- ret = clk_prepare_enable(data->clk);
- if (ret) {
- dev_err(&pdev->dev, "unable to enable uart clock - %d\n",
- ret);
- return ret;
+
+ mapbase = res->start;
+ mapsize = resource_size(res);
+
+ if (has_acpi_companion(&pdev->dev)) {
+ const struct acpi_device_id *match;
+
+ match =
acpi_match_device(pdev->dev.driver->acpi_match_table, &pdev->dev);
+ if (!match)
+ return -ENODEV;
+
+ acpi_data = (struct bcm2835_aux_serial_acpi_driver_data
*)match->driver_data;
+
+ /* 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.
