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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: Oskar Senft <osk@google.com>
Link: https://lore.kernel.org/r/20190905144130.220713-1-osk@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oskar Senft 2019-09-05 10:41:28 -04:00 committed by Greg Kroah-Hartman
parent a8afc19355
commit 8d310c9107
3 changed files with 95 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
Documentation/ABI/stable/sysfs-driver-aspeed-vuart
View File

@ -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

84
drivers/tty/serial/8250/8250_aspeed_vuart.c
View File

@ -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);

1
drivers/tty/serial/8250/Kconfig
View File

@ -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-