path: root/meta-openbmc-mods/meta-ast2600/recipes-kernel/linux/linux-aspeed/0004-Add-a-workaround-to-cover-UART-interrupt-bug-in-AST2.patch

From a9b43dbf68a4b5650dd98332243d4a2951717eb5 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 |  4 ++
 drivers/tty/serial/8250/8250_aspeed.c         | 56 ++++++++++++++++-
 drivers/tty/serial/8250/8250_early.c          |  1 +
 drivers/tty/serial/8250/8250_of.c             | 63 +++++++++++++++++++
 4 files changed, 123 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/aspeed-bmc-intel-ast2600.dts b/arch/arm/boot/dts/aspeed-bmc-intel-ast2600.dts
index c648c123c315..bf375634082c 100644
--- a/arch/arm/boot/dts/aspeed-bmc-intel-ast2600.dts
+++ b/arch/arm/boot/dts/aspeed-bmc-intel-ast2600.dts
@@ -392,6 +392,7 @@
 };
 
 &uart1 {
+	reg = <0x1e783000 0x20>, <0x1e6e2014 0x4>, <0x1e78307c 0x4>;
 	status = "okay";
 	pinctrl-0 = <&pinctrl_txd1_default
 		     &pinctrl_rxd1_default
@@ -404,6 +405,7 @@
 };
 
 &uart2 {
+	reg = <0x1e78d000 0x20>, <0x1e6e2014 0x4>, <0x1e78d07c 0x4>;
 	status = "okay";
 	pinctrl-0 = <&pinctrl_txd2_default
 		     &pinctrl_rxd2_default
@@ -416,11 +418,13 @@
 };
 
 &uart3 {
+	reg = <0x1e78e000 0x20>, <0x1e6e2014 0x4>, <0x1e78e07c 0x4>;
 	status = "okay";
 	pinctrl-0 = <>;
 };
 
 &uart4 {
+	reg = <0x1e78f000 0x20>, <0x1e6e2014 0x4>, <0x1e78f07c 0x4>;
 	status = "okay";
 	pinctrl-0 = <>;
 };
diff --git a/drivers/tty/serial/8250/8250_aspeed.c b/drivers/tty/serial/8250/8250_aspeed.c
index bb3955bb8c24..1ba4423d5e2f 100644
--- a/drivers/tty/serial/8250/8250_aspeed.c
+++ b/drivers/tty/serial/8250/8250_aspeed.c
@@ -74,6 +74,10 @@ struct ast8250_data {
 
 	struct ast8250_vuart vuart;
 	struct ast8250_udma dma;
+
+	struct workqueue_struct *work_queue;
+	struct delayed_work work_handler;
+	void __iomem *wa_base;
 };
 
 static void ast8250_dma_tx_complete(int tx_rb_rptr, void *id)
@@ -336,12 +340,25 @@ static int __maybe_unused ast8250_resume(struct device *dev)
 	return 0;
 }
 
+#define WA_DELAY_JIFFIES	msecs_to_jiffies(1)
+static void ast8250_clear_abnormal_int_flags(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct ast8250_data *data = container_of(dwork, struct ast8250_data,
+						 work_handler);
+
+	(void) readl(data->wa_base);
+	queue_delayed_work(data->work_queue, &data->work_handler,
+			   WA_DELAY_JIFFIES);
+}
+
 static int ast8250_probe(struct platform_device *pdev)
 {
 	int rc;
 	struct uart_8250_port uart = {};
 	struct uart_port *port = &uart.port;
 	struct device *dev = &pdev->dev;
+	void __iomem *chip_id_base;
 	struct ast8250_data *data;
 
 	struct resource *res;
@@ -454,6 +471,37 @@ static int ast8250_probe(struct platform_device *pdev)
 	pm_runtime_enable(&pdev->dev);
 
 	platform_set_drvdata(pdev, data);
+
+	#define REV_ID_AST2600A0 0x05000303
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!res || resource_size(res) < 2)
+		return 0;
+
+	data->wa_base = devm_platform_ioremap_resource(pdev, 2);
+	if (IS_ERR(data->wa_base))
+		return 0;
+
+	chip_id_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(chip_id_base))
+		return 0;
+
+	if (readl(chip_id_base) == REV_ID_AST2600A0) {
+		data->work_queue = alloc_ordered_workqueue(pdev->name, 0);
+		if (data->work_queue) {
+			INIT_DELAYED_WORK(&data->work_handler,
+					  ast8250_clear_abnormal_int_flags);
+			queue_delayed_work(data->work_queue,
+					   &data->work_handler,
+					   WA_DELAY_JIFFIES);
+			dev_info(dev, "AST2600 A0 WA initiated\n");
+		} else {
+			dev_err(dev, "Can't enable AST2600 A0 UART WA\n");
+		}
+	}
+
+	devm_iounmap(dev, chip_id_base);
+	devm_release_mem_region(dev, res->start, resource_size(res));
+
 	return 0;
 }
 
@@ -464,7 +512,13 @@ static int ast8250_remove(struct platform_device *pdev)
 	if (data->is_vuart)
 		ast8250_vuart_set_enable(data, false);
 
-    serial8250_unregister_port(data->line);
+	if (data->work_queue) {
+		cancel_delayed_work_sync(&data->work_handler);
+		destroy_workqueue(data->work_queue);
+	}
+
+	serial8250_unregister_port(data->line);
+
 	return 0;
 }
 
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index c171ce6db691..6d7bb63fe0c6 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 bce28729dd7b..6159d8af6fef 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
  */
@@ -233,6 +249,47 @@ 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);
@@ -254,6 +311,11 @@ 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);
@@ -324,6 +386,7 @@ static const struct of_device_id of_platform_serial_table[] = {
 	{ .compatible = "ti,da830-uart", .data = (void *)PORT_DA830, },
 	{ .compatible = "nuvoton,wpcm450-uart", .data = (void *)PORT_NPCM, },
 	{ .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