Commit 8d310c91 authored by Oskar Senft's avatar Oskar Senft Committed by Greg Kroah-Hartman
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drivers/tty/serial/8250: Make Aspeed VUART SIRQ polarity configurable 



Make the SIRQ polarity for Aspeed AST24xx/25xx VUART configurable via
sysfs. This setting need to be changed on specific host platforms
depending on the selected host interface (LPC / eSPI).

The setting is configurable via sysfs rather than device-tree to stay in
line with other related configurable settings.

On AST2500 the VUART SIRQ polarity can be auto-configured by reading a
bit from a configuration register, e.g. the LPC/eSPI interface
configuration bit.

Tested: Verified on TYAN S7106 mainboard.
Signed-off-by: default avatarOskar Senft <osk@google.com>
Link: https://lore.kernel.org/r/20190905144130.220713-1-osk@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a8afc193

Documentation/ABI/stable/sysfs-driver-aspeed-vuart

+10 −1
Original line number Diff line number Diff line
@@ -6,10 +6,19 @@ Description: Configures which IO port the host side of the UART 
Users:		OpenBMC.  Proposed changes should be mailed to

		openbmc@lists.ozlabs.org



What:		/sys/bus/platform/drivers/aspeed-vuart*/sirq

What:		/sys/bus/platform/drivers/aspeed-vuart/*/sirq

Date:		April 2017

Contact:	Jeremy Kerr <jk@ozlabs.org>

Description:	Configures which interrupt number the host side of

		the UART will appear on the host <-> BMC LPC bus.

Users:		OpenBMC.  Proposed changes should be mailed to

		openbmc@lists.ozlabs.org



What:		/sys/bus/platform/drivers/aspeed-vuart/*/sirq_polarity

Date:		July 2019

Contact:	Oskar Senft <osk@google.com>

Description:	Configures the polarity of the serial interrupt to the

		host via the BMC LPC bus.

		Set to 0 for active-low or 1 for active-high.

Users:		OpenBMC.  Proposed changes should be mailed to

		openbmc@lists.ozlabs.org

drivers/tty/serial/8250/8250_aspeed_vuart.c

+84 −0
Original line number Diff line number Diff line
@@ -14,6 +14,8 @@ 
#include <linux/of_address.h>

#include <linux/of_irq.h>

#include <linux/of_platform.h>

#include <linux/regmap.h>

#include <linux/mfd/syscon.h>

#include <linux/tty.h>

#include <linux/tty_flip.h>

#include <linux/clk.h>
@@ -22,6 +24,7 @@ 


#define ASPEED_VUART_GCRA		0x20

#define ASPEED_VUART_GCRA_VUART_EN		BIT(0)

#define ASPEED_VUART_GCRA_HOST_SIRQ_POLARITY	BIT(1)

#define ASPEED_VUART_GCRA_DISABLE_HOST_TX_DISCARD BIT(5)

#define ASPEED_VUART_GCRB		0x24

#define ASPEED_VUART_GCRB_HOST_SIRQ_MASK	GENMASK(7, 4)
@@ -131,8 +134,53 @@ static ssize_t sirq_store(struct device *dev, struct device_attribute *attr, 


static DEVICE_ATTR_RW(sirq);



static ssize_t sirq_polarity_show(struct device *dev,

				  struct device_attribute *attr, char *buf)

{

	struct aspeed_vuart *vuart = dev_get_drvdata(dev);

	u8 reg;



	reg = readb(vuart->regs + ASPEED_VUART_GCRA);

	reg &= ASPEED_VUART_GCRA_HOST_SIRQ_POLARITY;



	return snprintf(buf, PAGE_SIZE - 1, "%u\n", reg ? 1 : 0);

}



static void aspeed_vuart_set_sirq_polarity(struct aspeed_vuart *vuart,

					   bool polarity)

{

	u8 reg = readb(vuart->regs + ASPEED_VUART_GCRA);



	if (polarity)

		reg |= ASPEED_VUART_GCRA_HOST_SIRQ_POLARITY;

	else

		reg &= ~ASPEED_VUART_GCRA_HOST_SIRQ_POLARITY;



	writeb(reg, vuart->regs + ASPEED_VUART_GCRA);

}



static ssize_t sirq_polarity_store(struct device *dev,

				   struct device_attribute *attr,

				   const char *buf, size_t count)

{

	struct aspeed_vuart *vuart = dev_get_drvdata(dev);

	unsigned long val;

	int err;



	err = kstrtoul(buf, 0, &val);

	if (err)

		return err;



	aspeed_vuart_set_sirq_polarity(vuart, val != 0);



	return count;

}



static DEVICE_ATTR_RW(sirq_polarity);



static struct attribute *aspeed_vuart_attrs[] = {

	&dev_attr_sirq.attr,

	&dev_attr_sirq_polarity.attr,

	&dev_attr_lpc_address.attr,

	NULL,

};
@@ -302,8 +350,30 @@ static int aspeed_vuart_handle_irq(struct uart_port *port) 
	return 1;

}



static void aspeed_vuart_auto_configure_sirq_polarity(

	struct aspeed_vuart *vuart, struct device_node *syscon_np,

	u32 reg_offset, u32 reg_mask)

{

	struct regmap *regmap;

	u32 value;



	regmap = syscon_node_to_regmap(syscon_np);

	if (IS_ERR(regmap)) {

		dev_warn(vuart->dev,

			 "could not get regmap for aspeed,sirq-polarity-sense\n");

		return;

	}

	if (regmap_read(regmap, reg_offset, &value)) {

		dev_warn(vuart->dev, "could not read hw strap table\n");

		return;

	}



	aspeed_vuart_set_sirq_polarity(vuart, (value & reg_mask) == 0);

}



static int aspeed_vuart_probe(struct platform_device *pdev)

{

	struct of_phandle_args sirq_polarity_sense_args;

	struct uart_8250_port port;

	struct aspeed_vuart *vuart;

	struct device_node *np;
@@ -402,6 +472,20 @@ static int aspeed_vuart_probe(struct platform_device *pdev) 


	vuart->line = rc;



	rc = of_parse_phandle_with_fixed_args(

		np, "aspeed,sirq-polarity-sense", 2, 0,

		&sirq_polarity_sense_args);

	if (rc < 0) {

		dev_dbg(&pdev->dev,

			"aspeed,sirq-polarity-sense property not found\n");

	} else {

		aspeed_vuart_auto_configure_sirq_polarity(

			vuart, sirq_polarity_sense_args.np,

			sirq_polarity_sense_args.args[0],

			BIT(sirq_polarity_sense_args.args[1]));

		of_node_put(sirq_polarity_sense_args.np);

	}



	aspeed_vuart_set_enabled(vuart, true);

	aspeed_vuart_set_host_tx_discard(vuart, true);

	platform_set_drvdata(pdev, vuart);

drivers/tty/serial/8250/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -243,6 +243,7 @@ config SERIAL_8250_ASPEED_VUART 
	tristate "Aspeed Virtual UART"

	depends on SERIAL_8250

	depends on OF

	depends on REGMAP && MFD_SYSCON

	help

	  If you want to use the virtual UART (VUART) device on Aspeed

	  BMC platforms, enable this option. This enables the 16550A-

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