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From 0177d25a23d56bca91fa7938d786b709fd7fba3e 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>
---
arch/arm/boot/dts/aspeed-g6.dtsi | 20 ++++++-------
drivers/tty/serial/8250/8250_of.c | 63 +++++++++++++++++++++++++++++++++++++++
2 files changed, 73 insertions(+), 10 deletions(-)
diff --git a/arch/arm/boot/dts/aspeed-g6.dtsi b/arch/arm/boot/dts/aspeed-g6.dtsi
index 656053386fe8..91f431e419d9 100644
--- a/arch/arm/boot/dts/aspeed-g6.dtsi
+++ b/arch/arm/boot/dts/aspeed-g6.dtsi
@@ -502,8 +502,8 @@
};
uart1: serial@1e783000 {
- compatible = "ns16550a";
- reg = <0x1e783000 0x20>;
+ compatible = "aspeed,ast2600-uart";
+ reg = <0x1e783000 0x20>, <0x1e6e2014 0x4>, <0x1e78307c 0x4>;
reg-shift = <2>;
reg-io-width = <4>;
interrupts = <GIC_SPI 47 IRQ_TYPE_LEVEL_HIGH>;
@@ -516,8 +516,8 @@
};
uart5: serial@1e784000 {
- compatible = "ns16550a";
- reg = <0x1e784000 0x1000>;
+ compatible = "aspeed,ast2600-uart";
+ reg = <0x1e784000 0x20>, <0x1e6e2014 0x4>, <0x1e78407c 0x4>;
reg-shift = <2>;
interrupts = <GIC_SPI 8 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&syscon ASPEED_CLK_GATE_UART5CLK>;
@@ -744,8 +744,8 @@
};
uart2: serial@1e78d000 {
- compatible = "ns16550a";
- reg = <0x1e78d000 0x20>;
+ compatible = "aspeed,ast2600-uart";
+ reg = <0x1e78d000 0x20>, <0x1e6e2014 0x4>, <0x1e78d07c 0x4>;
reg-shift = <2>;
reg-io-width = <4>;
interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
@@ -758,8 +758,8 @@
};
uart3: serial@1e78e000 {
- compatible = "ns16550a";
- reg = <0x1e78e000 0x20>;
+ compatible = "aspeed,ast2600-uart";
+ reg = <0x1e78e000 0x20>, <0x1e6e2014 0x4>, <0x1e78e07c 0x4>;
reg-shift = <2>;
reg-io-width = <4>;
interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
@@ -772,8 +772,8 @@
};
uart4: serial@1e78f000 {
- compatible = "ns16550a";
- reg = <0x1e78f000 0x20>;
+ compatible = "aspeed,ast2600-uart";
+ reg = <0x1e78f000 0x20>, <0x1e6e2014 0x4>, <0x1e78f07c 0x4>;
reg-shift = <2>;
reg-io-width = <4>;
interrupts = <GIC_SPI 50 IRQ_TYPE_LEVEL_HIGH>;
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 9ba31701a372..53850f859424 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -16,6 +16,7 @@
#include <linux/pm_runtime.h>
#include <linux/clk.h>
#include <linux/reset.h>
+#include <linux/workqueue.h>
#include "8250.h"
@@ -24,6 +25,9 @@ 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;
};
#ifdef CONFIG_ARCH_TEGRA
@@ -202,6 +206,18 @@ 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
*/
@@ -250,6 +266,47 @@ 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);
@@ -271,6 +328,11 @@ 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);
@@ -341,6 +403,7 @@ 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);
--
2.7.4
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