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From a136d2c30b850f94ee7b39f842eaede8c0a1c490 Mon Sep 17 00:00:00 2001
From: Jae Hyun Yoo <jae.hyun.yoo@intel.com>
Date: Mon, 27 Apr 2020 12:11:06 -0700
Subject: [PATCH] Add a workaround to cover UART interrupt bug in AST2600 A0
This commit adds a workaround to cover UART interrupt bug in
AST2600 A0 revision. It makes infinite reading on the UART +0x7c
register for clearing abnormal interrupts in every milli-second.
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@intel.com>
---
.../arm/boot/dts/aspeed-bmc-intel-ast2600.dts | 8 +++
drivers/tty/serial/8250/8250_early.c | 1 +
drivers/tty/serial/8250/8250_of.c | 63 +++++++++++++++++++
3 files changed, 72 insertions(+)
diff --git a/arch/arm/boot/dts/aspeed-bmc-intel-ast2600.dts b/arch/arm/boot/dts/aspeed-bmc-intel-ast2600.dts
index 3218884b90f4..08e1f060341e 100644
--- a/arch/arm/boot/dts/aspeed-bmc-intel-ast2600.dts
+++ b/arch/arm/boot/dts/aspeed-bmc-intel-ast2600.dts
@@ -375,6 +375,8 @@
};
&uart1 {
+ compatible = "aspeed,ast2600-uart";
+ reg = <0x1e783000 0x20>, <0x1e6e2014 0x4>, <0x1e78307c 0x4>;
status = "okay";
pinctrl-0 = <&pinctrl_txd1_default
&pinctrl_rxd1_default
@@ -387,6 +389,8 @@
};
&uart2 {
+ compatible = "aspeed,ast2600-uart";
+ reg = <0x1e78d000 0x20>, <0x1e6e2014 0x4>, <0x1e78d07c 0x4>;
status = "okay";
pinctrl-0 = <&pinctrl_txd2_default
&pinctrl_rxd2_default
@@ -399,11 +403,15 @@
};
&uart3 {
+ compatible = "aspeed,ast2600-uart";
+ reg = <0x1e78e000 0x20>, <0x1e6e2014 0x4>, <0x1e78e07c 0x4>;
status = "okay";
pinctrl-0 = <>;
};
&uart4 {
+ compatible = "aspeed,ast2600-uart";
+ reg = <0x1e78f000 0x20>, <0x1e6e2014 0x4>, <0x1e78f07c 0x4>;
status = "okay";
pinctrl-0 = <>;
};
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 70d7826788f5..56c4725e1b04 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -180,6 +180,7 @@ OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup);
OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
OF_EARLYCON_DECLARE(uart, "nvidia,tegra20-uart", early_serial8250_setup);
OF_EARLYCON_DECLARE(uart, "snps,dw-apb-uart", early_serial8250_setup);
+OF_EARLYCON_DECLARE(uart, "aspeed,ast2600-uart", early_serial8250_setup);
#ifdef CONFIG_SERIAL_8250_OMAP
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 65e9045dafe6..4d94c9f6a422 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -15,6 +15,7 @@
#include <linux/pm_runtime.h>
#include <linux/clk.h>
#include <linux/reset.h>
+#include <linux/workqueue.h>
#include "8250.h"
@@ -23,6 +24,9 @@ struct of_serial_info {
struct reset_control *rst;
int type;
int line;
+ struct workqueue_struct *work_queue;
+ struct delayed_work work_handler;
+ void __iomem *wa_base;
};
/*
@@ -181,6 +185,18 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
return ret;
}
+#define WA_DELAY_JIFFIES msecs_to_jiffies(1)
+static void clear_abnormal_int_flags(struct work_struct *work)
+{
+ struct delayed_work *dwork = to_delayed_work(work);
+ struct of_serial_info *info = container_of(dwork, struct of_serial_info,
+ work_handler);
+
+ (void) readl(info->wa_base);
+ queue_delayed_work(info->work_queue, &info->work_handler,
+ WA_DELAY_JIFFIES);
+}
+
/*
* Try to register a serial port
*/
@@ -229,6 +245,47 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
if (ret < 0)
goto err_dispose;
+ if (of_device_is_compatible(ofdev->dev.of_node,
+ "aspeed,ast2600-uart")) {
+ #define REV_ID_AST2600A0 0x05000303
+ void __iomem *chip_id_base;
+ struct resource *res = platform_get_resource(ofdev,
+ IORESOURCE_MEM, 1);
+
+ if (!res || resource_size(res) < 2)
+ goto skip_wa;
+
+ info->wa_base = devm_platform_ioremap_resource(ofdev, 2);
+ if (IS_ERR(info->wa_base))
+ goto skip_wa;
+
+ chip_id_base = devm_ioremap_resource(&ofdev->dev, res);
+ if (IS_ERR(chip_id_base))
+ goto skip_wa;
+
+ if (readl(chip_id_base) == REV_ID_AST2600A0) {
+ info->work_queue = alloc_ordered_workqueue(ofdev->name,
+ 0);
+ if (info->work_queue) {
+ INIT_DELAYED_WORK(&info->work_handler,
+ clear_abnormal_int_flags);
+ queue_delayed_work(info->work_queue,
+ &info->work_handler,
+ WA_DELAY_JIFFIES);
+ dev_info(&ofdev->dev,
+ "AST2600 A0 WA initiated\n");
+ } else {
+ dev_err(&ofdev->dev,
+ "Can't enable AST2600 A0 UART WA\n");
+ }
+ }
+
+ devm_iounmap(&ofdev->dev, chip_id_base);
+ devm_release_mem_region(&ofdev->dev, res->start,
+ resource_size(res));
+ }
+
+skip_wa:
info->type = port_type;
info->line = ret;
platform_set_drvdata(ofdev, info);
@@ -250,6 +307,11 @@ static int of_platform_serial_remove(struct platform_device *ofdev)
{
struct of_serial_info *info = platform_get_drvdata(ofdev);
+ if (info->work_queue) {
+ cancel_delayed_work_sync(&info->work_handler);
+ destroy_workqueue(info->work_queue);
+ }
+
serial8250_unregister_port(info->line);
reset_control_assert(info->rst);
@@ -319,6 +381,7 @@ static const struct of_device_id of_platform_serial_table[] = {
.data = (void *)PORT_XSCALE, },
{ .compatible = "ti,da830-uart", .data = (void *)PORT_DA830, },
{ .compatible = "nuvoton,npcm750-uart", .data = (void *)PORT_NPCM, },
+ { .compatible = "aspeed,ast2600-uart", .data = (void *)PORT_16550A, },
{ /* end of list */ },
};
MODULE_DEVICE_TABLE(of, of_platform_serial_table);
--
2.17.1
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