diff mbox series

[1/2] soc: aspeed: Add LPC UART routing support

Message ID 20210901062216.32675-2-chiawei_wang@aspeedtech.com (mailing list archive)
State New, archived
Headers show
Series arm: aspeed: Add LPC uart routing support | expand

Commit Message

ChiaWei Wang Sept. 1, 2021, 6:22 a.m. UTC 
Add driver support for the LPC UART routing control. Users can perform
runtime configuration of the RX muxes among the UART controllers and the
UART TXD/RXD IO pins. This is achieved through the exported sysfs interface.

Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
---
 drivers/soc/aspeed/Kconfig                   |  11 +
 drivers/soc/aspeed/Makefile                  |   9 +-
 drivers/soc/aspeed/aspeed-lpc-uart-routing.c | 621 +++++++++++++++++++
 3 files changed, 637 insertions(+), 4 deletions(-)
 create mode 100644 drivers/soc/aspeed/aspeed-lpc-uart-routing.c

Comments

Joel Stanley Sept. 1, 2021, 7:36 a.m. UTC | #1 
On Wed, 1 Sept 2021 at 06:22, Chia-Wei Wang <chiawei_wang@aspeedtech.com> wrote:
>
> Add driver support for the LPC UART routing control. Users can perform

As we discussed, remove the "LPC" part of the name.

> runtime configuration of the RX muxes among the UART controllers and the
> UART TXD/RXD IO pins. This is achieved through the exported sysfs interface.
>
> Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>

It would be good to have some example of how to use it, and the output
from sysfs.

You should also add a patch to document the sysfs files in Documentation/ABI.

> +++ b/drivers/soc/aspeed/aspeed-lpc-uart-routing.c
> @@ -0,0 +1,621 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) 2018 Google LLC
> + * Copyright (c) 2021 Aspeed Technology Inc.
> + */
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/of_address.h>

You can drop this one.

> +#include <linux/of_platform.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
> +#include <linux/platform_device.h>
> +
> +/* register offsets */
> +#define HICR9  0x98
> +#define HICRA  0x9c
> +
> +/* attributes options */
> +#define UART_ROUTING_IO1       "io1"
> +#define UART_ROUTING_IO2       "io2"
> +#define UART_ROUTING_IO3       "io3"
> +#define UART_ROUTING_IO4       "io4"
> +#define UART_ROUTING_IO5       "io5"
> +#define UART_ROUTING_IO6       "io6"
> +#define UART_ROUTING_IO10      "io10"
> +#define UART_ROUTING_UART1     "uart1"
> +#define UART_ROUTING_UART2     "uart2"
> +#define UART_ROUTING_UART3     "uart3"
> +#define UART_ROUTING_UART4     "uart4"
> +#define UART_ROUTING_UART5     "uart5"
> +#define UART_ROUTING_UART6     "uart6"
> +#define UART_ROUTING_UART10    "uart10"
> +#define UART_ROUTING_RES       "reserved"
> +
> +struct aspeed_uart_routing {
> +       struct regmap *map;
> +       spinlock_t lock;
> +       struct attribute_group const *attr_grp;
> +};
> +
> +struct aspeed_uart_routing_selector {
> +       struct device_attribute dev_attr;
> +       uint32_t reg;
> +       uint32_t mask;
> +       uint32_t shift;

These can be u8.

> +static ssize_t aspeed_uart_routing_show(struct device *dev,
> +                                       struct device_attribute *attr,
> +                                       char *buf)
> +{
> +       struct aspeed_uart_routing *uart_routing = dev_get_drvdata(dev);
> +       struct aspeed_uart_routing_selector *sel = to_routing_selector(attr);
> +       int val, pos, len;
> +
> +       regmap_read(uart_routing->map, sel->reg, &val);
> +       val = (val >> sel->shift) & sel->mask;
> +
> +       len = 0;
> +       for (pos = 0; sel->options[pos] != NULL; ++pos) {
> +               if (pos == val) {
> +                       len += snprintf(buf + len, PAGE_SIZE - 1 - len,
> +                                       "[%s] ", sel->options[pos]);
> +               } else {
> +                       len += snprintf(buf + len, PAGE_SIZE - 1 - len,
> +                                       "%s ", sel->options[pos]);

The kernel prefers sysfs_emit and sysfs_emit_at insteading of using
snprintf directly.

> +               }
> +       }
> +
> +       if (val >= pos) {
> +               len += snprintf(buf + len, PAGE_SIZE - 1 - len,
> +                               "[unknown(%d)]", val);
> +       }
> +
> +       len += snprintf(buf + len, PAGE_SIZE - 1 - len, "\n");
> +
> +       return len;
> +}
> +
> +static ssize_t aspeed_uart_routing_store(struct device *dev,
> +                                        struct device_attribute *attr,
> +                                        const char *buf, size_t count)
> +{
> +       unsigned long flags;
> +       struct aspeed_uart_routing *uart_routing = dev_get_drvdata(dev);
> +       struct aspeed_uart_routing_selector *sel = to_routing_selector(attr);
> +       int val;
> +
> +       val = match_string(sel->options, -1, buf);
> +       if (val < 0) {
> +               dev_err(dev, "invalid value \"%s\"\n", buf);
> +               return -EINVAL;
> +       }
> +
> +       spin_lock_irqsave(&uart_routing->lock, flags);

I can't see why you would need a spinlock here. The regmap has it's
own locking so it will protect against concurrent updates to the
registers.

> +
> +       regmap_update_bits(uart_routing->map, sel->reg,
> +                       (sel->mask << sel->shift),
> +                       (val & sel->mask) << sel->shift);
> +
> +       spin_unlock_irqrestore(&uart_routing->lock, flags);
> +
> +       return count;
> +}
> +
> +static int aspeed_uart_routing_probe(struct platform_device *pdev)
> +{
> +       int rc;
> +       struct device *dev = &pdev->dev;
> +       struct aspeed_uart_routing *uart_routing;
> +
> +       uart_routing = devm_kzalloc(&pdev->dev,
> +                                   sizeof(*uart_routing),
> +                                   GFP_KERNEL);

You can reformat this file to have longer lines; the kernel is ok with
up to 100 columsn these days.

> +       if (!uart_routing) {
> +               dev_err(dev, "cannot allocate memory\n");

I'd drop this error message.

> +               return -ENOMEM;
> +       }
> +
> +       uart_routing->map = syscon_node_to_regmap(dev->parent->of_node);
> +       if (IS_ERR(uart_routing->map)) {
> +               dev_err(dev, "cannot get regmap\n");
> +               return PTR_ERR(uart_routing->map);
> +       }
> +
> +       uart_routing->attr_grp = of_device_get_match_data(dev);
> +
> +       spin_lock_init(&uart_routing->lock);

I don't think you need the lock at all.

Cheers,

Joel
ChiaWei Wang Sept. 1, 2021, 9:43 a.m. UTC | #2 
> -----Original Message-----
> From: Joel Stanley <joel@jms.id.au>
> Sent: Wednesday, September 1, 2021 3:37 PM
> 
> On Wed, 1 Sept 2021 at 06:22, Chia-Wei Wang
> <chiawei_wang@aspeedtech.com> wrote:
> >
> > Add driver support for the LPC UART routing control. Users can perform
> 
> As we discussed, remove the "LPC" part of the name.
> 
> > runtime configuration of the RX muxes among the UART controllers and
> > the UART TXD/RXD IO pins. This is achieved through the exported sysfs
> interface.
> >
> > Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
> 
> It would be good to have some example of how to use it, and the output from
> sysfs.
> 
> You should also add a patch to document the sysfs files in Documentation/ABI.
> 

Will add a new commit for the sysfs description.

> > +++ b/drivers/soc/aspeed/aspeed-lpc-uart-routing.c
> > @@ -0,0 +1,621 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (c) 2018 Google LLC
> > + * Copyright (c) 2021 Aspeed Technology Inc.
> > + */
> > +#include <linux/device.h>
> > +#include <linux/module.h>
> > +#include <linux/of_device.h>
> > +#include <linux/of_address.h>
> 
> You can drop this one.

Revised as suggested.

> 
> > +#include <linux/of_platform.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/regmap.h>
> > +#include <linux/platform_device.h>
> > +
> > +/* register offsets */
> > +#define HICR9  0x98
> > +#define HICRA  0x9c
> > +
> > +/* attributes options */
> > +#define UART_ROUTING_IO1       "io1"
> > +#define UART_ROUTING_IO2       "io2"
> > +#define UART_ROUTING_IO3       "io3"
> > +#define UART_ROUTING_IO4       "io4"
> > +#define UART_ROUTING_IO5       "io5"
> > +#define UART_ROUTING_IO6       "io6"
> > +#define UART_ROUTING_IO10      "io10"
> > +#define UART_ROUTING_UART1     "uart1"
> > +#define UART_ROUTING_UART2     "uart2"
> > +#define UART_ROUTING_UART3     "uart3"
> > +#define UART_ROUTING_UART4     "uart4"
> > +#define UART_ROUTING_UART5     "uart5"
> > +#define UART_ROUTING_UART6     "uart6"
> > +#define UART_ROUTING_UART10    "uart10"
> > +#define UART_ROUTING_RES       "reserved"
> > +
> > +struct aspeed_uart_routing {
> > +       struct regmap *map;
> > +       spinlock_t lock;
> > +       struct attribute_group const *attr_grp; };
> > +
> > +struct aspeed_uart_routing_selector {
> > +       struct device_attribute dev_attr;
> > +       uint32_t reg;
> > +       uint32_t mask;
> > +       uint32_t shift;
> 
> These can be u8.

Revised as suggested.

> 
> > +static ssize_t aspeed_uart_routing_show(struct device *dev,
> > +                                       struct device_attribute
> *attr,
> > +                                       char *buf) {
> > +       struct aspeed_uart_routing *uart_routing = dev_get_drvdata(dev);
> > +       struct aspeed_uart_routing_selector *sel =
> to_routing_selector(attr);
> > +       int val, pos, len;
> > +
> > +       regmap_read(uart_routing->map, sel->reg, &val);
> > +       val = (val >> sel->shift) & sel->mask;
> > +
> > +       len = 0;
> > +       for (pos = 0; sel->options[pos] != NULL; ++pos) {
> > +               if (pos == val) {
> > +                       len += snprintf(buf + len, PAGE_SIZE - 1 - len,
> > +                                       "[%s] ", sel->options[pos]);
> > +               } else {
> > +                       len += snprintf(buf + len, PAGE_SIZE - 1 - len,
> > +                                       "%s ", sel->options[pos]);
> 
> The kernel prefers sysfs_emit and sysfs_emit_at insteading of using snprintf
> directly.

Revised as suggested.

> 
> > +               }
> > +       }
> > +
> > +       if (val >= pos) {
> > +               len += snprintf(buf + len, PAGE_SIZE - 1 - len,
> > +                               "[unknown(%d)]", val);
> > +       }
> > +
> > +       len += snprintf(buf + len, PAGE_SIZE - 1 - len, "\n");
> > +
> > +       return len;
> > +}
> > +
> > +static ssize_t aspeed_uart_routing_store(struct device *dev,
> > +                                        struct device_attribute
> *attr,
> > +                                        const char *buf, size_t
> > +count) {
> > +       unsigned long flags;
> > +       struct aspeed_uart_routing *uart_routing = dev_get_drvdata(dev);
> > +       struct aspeed_uart_routing_selector *sel =
> to_routing_selector(attr);
> > +       int val;
> > +
> > +       val = match_string(sel->options, -1, buf);
> > +       if (val < 0) {
> > +               dev_err(dev, "invalid value \"%s\"\n", buf);
> > +               return -EINVAL;
> > +       }
> > +
> > +       spin_lock_irqsave(&uart_routing->lock, flags);
> 
> I can't see why you would need a spinlock here. The regmap has it's own
> locking so it will protect against concurrent updates to the registers.

You are right. Lock is not needed here. Will removed it as suggested.

> 
> > +
> > +       regmap_update_bits(uart_routing->map, sel->reg,
> > +                       (sel->mask << sel->shift),
> > +                       (val & sel->mask) << sel->shift);
> > +
> > +       spin_unlock_irqrestore(&uart_routing->lock, flags);
> > +
> > +       return count;
> > +}
> > +
> > +static int aspeed_uart_routing_probe(struct platform_device *pdev) {
> > +       int rc;
> > +       struct device *dev = &pdev->dev;
> > +       struct aspeed_uart_routing *uart_routing;
> > +
> > +       uart_routing = devm_kzalloc(&pdev->dev,
> > +                                   sizeof(*uart_routing),
> > +                                   GFP_KERNEL);
> 
> You can reformat this file to have longer lines; the kernel is ok with up to 100
> columsn these days.
> 
> > +       if (!uart_routing) {
> > +               dev_err(dev, "cannot allocate memory\n");
> 
> I'd drop this error message.

Revised as suggested

> 
> > +               return -ENOMEM;
> > +       }
> > +
> > +       uart_routing->map =
> syscon_node_to_regmap(dev->parent->of_node);
> > +       if (IS_ERR(uart_routing->map)) {
> > +               dev_err(dev, "cannot get regmap\n");
> > +               return PTR_ERR(uart_routing->map);
> > +       }
> > +
> > +       uart_routing->attr_grp = of_device_get_match_data(dev);
> > +
> > +       spin_lock_init(&uart_routing->lock);
> 
> I don't think you need the lock at all.

Same as above.

Thanks for reviewing this.
The v2 patch will include the driver refactoring and additional documentation.

Chiawei
diff mbox series

Patch

diff --git a/drivers/soc/aspeed/Kconfig b/drivers/soc/aspeed/Kconfig
index 243ca196e6ad..6866757e6be2 100644
--- a/drivers/soc/aspeed/Kconfig
+++ b/drivers/soc/aspeed/Kconfig
@@ -24,6 +24,17 @@  config ASPEED_LPC_SNOOP
 	  allows the BMC to listen on and save the data written by
 	  the host to an arbitrary LPC I/O port.
 
+config ASPEED_LPC_UART_ROUTING
+	tristate "ASPEED LPC uart routing control"
+	select REGMAP
+	select MFD_SYSCON
+	default ARCH_ASPEED
+	help
+	  Provides a driver to control the LPC UART routing paths.
+	  An sysfs interface is exported allowing users to perform
+	  runtime configuration of the RX muxes between the UART
+	  controllers and I/O pins.
+
 config ASPEED_P2A_CTRL
 	tristate "ASPEED P2A (VGA MMIO to BMC) bridge control"
 	select REGMAP
diff --git a/drivers/soc/aspeed/Makefile b/drivers/soc/aspeed/Makefile
index fcab7192e1a4..87ad6578ddbb 100644
--- a/drivers/soc/aspeed/Makefile
+++ b/drivers/soc/aspeed/Makefile
@@ -1,5 +1,6 @@ 
 # SPDX-License-Identifier: GPL-2.0-only
-obj-$(CONFIG_ASPEED_LPC_CTRL)	+= aspeed-lpc-ctrl.o
-obj-$(CONFIG_ASPEED_LPC_SNOOP)	+= aspeed-lpc-snoop.o
-obj-$(CONFIG_ASPEED_P2A_CTRL)	+= aspeed-p2a-ctrl.o
-obj-$(CONFIG_ASPEED_SOCINFO)	+= aspeed-socinfo.o
+obj-$(CONFIG_ASPEED_LPC_CTRL)		+= aspeed-lpc-ctrl.o
+obj-$(CONFIG_ASPEED_LPC_SNOOP)		+= aspeed-lpc-snoop.o
+obj-$(CONFIG_ASPEED_LPC_UART_ROUTING)	+= aspeed-lpc-uart-routing.o
+obj-$(CONFIG_ASPEED_P2A_CTRL)		+= aspeed-p2a-ctrl.o
+obj-$(CONFIG_ASPEED_SOCINFO)		+= aspeed-socinfo.o
diff --git a/drivers/soc/aspeed/aspeed-lpc-uart-routing.c b/drivers/soc/aspeed/aspeed-lpc-uart-routing.c
new file mode 100644
index 000000000000..141d0d08b4ff
--- /dev/null
+++ b/drivers/soc/aspeed/aspeed-lpc-uart-routing.c
@@ -0,0 +1,621 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2018 Google LLC
+ * Copyright (c) 2021 Aspeed Technology Inc.
+ */
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/platform_device.h>
+
+/* register offsets */
+#define HICR9	0x98
+#define HICRA	0x9c
+
+/* attributes options */
+#define UART_ROUTING_IO1	"io1"
+#define UART_ROUTING_IO2	"io2"
+#define UART_ROUTING_IO3	"io3"
+#define UART_ROUTING_IO4	"io4"
+#define UART_ROUTING_IO5	"io5"
+#define UART_ROUTING_IO6	"io6"
+#define UART_ROUTING_IO10	"io10"
+#define UART_ROUTING_UART1	"uart1"
+#define UART_ROUTING_UART2	"uart2"
+#define UART_ROUTING_UART3	"uart3"
+#define UART_ROUTING_UART4	"uart4"
+#define UART_ROUTING_UART5	"uart5"
+#define UART_ROUTING_UART6	"uart6"
+#define UART_ROUTING_UART10	"uart10"
+#define UART_ROUTING_RES	"reserved"
+
+struct aspeed_uart_routing {
+	struct regmap *map;
+	spinlock_t lock;
+	struct attribute_group const *attr_grp;
+};
+
+struct aspeed_uart_routing_selector {
+	struct device_attribute	dev_attr;
+	uint32_t reg;
+	uint32_t mask;
+	uint32_t shift;
+	const char *const options[];
+};
+
+#define to_routing_selector(_dev_attr)					\
+	container_of(_dev_attr, struct aspeed_uart_routing_selector, dev_attr)
+
+static ssize_t aspeed_uart_routing_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf);
+
+static ssize_t aspeed_uart_routing_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count);
+
+#define ROUTING_ATTR(_name) {					\
+	.attr = {.name = _name,					\
+		 .mode = VERIFY_OCTAL_PERMISSIONS(0644) },	\
+	.show = aspeed_uart_routing_show,			\
+	.store = aspeed_uart_routing_store,			\
+}
+
+/* routing selector for AST25xx */
+static struct aspeed_uart_routing_selector ast2500_io6_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO6),
+	.reg = HICR9,
+	.shift = 8,
+	.mask = 0xf,
+	.options = {
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART5,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO5,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2500_uart5_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART5),
+	.reg = HICRA,
+	.shift = 28,
+	.mask = 0xf,
+	.options = {
+		    UART_ROUTING_IO5,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_IO6,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2500_uart4_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART4),
+	.reg = HICRA,
+	.shift = 25,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_IO6,
+		    NULL,
+	},
+};
+
+static struct aspeed_uart_routing_selector ast2500_uart3_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART3),
+	.reg = HICRA,
+	.shift = 22,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_IO6,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2500_uart2_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART2),
+	.reg = HICRA,
+	.shift = 19,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_IO6,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2500_uart1_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART1),
+	.reg = HICRA,
+	.shift = 16,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_IO6,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2500_io5_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO5),
+	.reg = HICRA,
+	.shift = 12,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_UART5,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO6,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2500_io4_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO4),
+	.reg = HICRA,
+	.shift = 9,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART5,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO6,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2500_io3_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO3),
+	.reg = HICRA,
+	.shift = 6,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART5,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO6,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2500_io2_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO2),
+	.reg = HICRA,
+	.shift = 3,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART5,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO6,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2500_io1_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO1),
+	.reg = HICRA,
+	.shift = 0,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART5,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO6,
+		    NULL,
+		    },
+};
+
+static struct attribute *ast2500_uart_routing_attrs[] = {
+	&ast2500_io6_sel.dev_attr.attr,
+	&ast2500_uart5_sel.dev_attr.attr,
+	&ast2500_uart4_sel.dev_attr.attr,
+	&ast2500_uart3_sel.dev_attr.attr,
+	&ast2500_uart2_sel.dev_attr.attr,
+	&ast2500_uart1_sel.dev_attr.attr,
+	&ast2500_io5_sel.dev_attr.attr,
+	&ast2500_io4_sel.dev_attr.attr,
+	&ast2500_io3_sel.dev_attr.attr,
+	&ast2500_io2_sel.dev_attr.attr,
+	&ast2500_io1_sel.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ast2500_uart_routing_attr_group = {
+	.attrs = ast2500_uart_routing_attrs,
+};
+
+/* routing selector for AST26xx */
+static struct aspeed_uart_routing_selector ast2600_uart10_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART10),
+	.reg = HICR9,
+	.shift = 12,
+	.mask = 0xf,
+	.options = {
+		    UART_ROUTING_IO10,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+			UART_ROUTING_RES,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2600_io10_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO10),
+	.reg = HICR9,
+	.shift = 8,
+	.mask = 0xf,
+	.options = {
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+			UART_ROUTING_RES,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+			UART_ROUTING_RES,
+		    UART_ROUTING_UART10,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2600_uart4_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART4),
+	.reg = HICRA,
+	.shift = 25,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_IO10,
+		    NULL,
+	},
+};
+
+static struct aspeed_uart_routing_selector ast2600_uart3_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART3),
+	.reg = HICRA,
+	.shift = 22,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_IO10,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2600_uart2_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART2),
+	.reg = HICRA,
+	.shift = 19,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_IO10,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2600_uart1_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_UART1),
+	.reg = HICRA,
+	.shift = 16,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_IO10,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2600_io4_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO4),
+	.reg = HICRA,
+	.shift = 9,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART10,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO10,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2600_io3_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO3),
+	.reg = HICRA,
+	.shift = 6,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART10,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_IO1,
+		    UART_ROUTING_IO2,
+		    UART_ROUTING_IO10,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2600_io2_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO2),
+	.reg = HICRA,
+	.shift = 3,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART10,
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO10,
+		    NULL,
+		    },
+};
+
+static struct aspeed_uart_routing_selector ast2600_io1_sel = {
+	.dev_attr = ROUTING_ATTR(UART_ROUTING_IO1),
+	.reg = HICRA,
+	.shift = 0,
+	.mask = 0x7,
+	.options = {
+		    UART_ROUTING_UART1,
+		    UART_ROUTING_UART2,
+		    UART_ROUTING_UART3,
+		    UART_ROUTING_UART4,
+		    UART_ROUTING_UART10,
+		    UART_ROUTING_IO3,
+		    UART_ROUTING_IO4,
+		    UART_ROUTING_IO10,
+		    NULL,
+		    },
+};
+
+static struct attribute *ast2600_uart_routing_attrs[] = {
+	&ast2600_uart10_sel.dev_attr.attr,
+	&ast2600_io10_sel.dev_attr.attr,
+	&ast2600_uart4_sel.dev_attr.attr,
+	&ast2600_uart3_sel.dev_attr.attr,
+	&ast2600_uart2_sel.dev_attr.attr,
+	&ast2600_uart1_sel.dev_attr.attr,
+	&ast2600_io4_sel.dev_attr.attr,
+	&ast2600_io3_sel.dev_attr.attr,
+	&ast2600_io2_sel.dev_attr.attr,
+	&ast2600_io1_sel.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ast2600_uart_routing_attr_group = {
+	.attrs = ast2600_uart_routing_attrs,
+};
+
+static ssize_t aspeed_uart_routing_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct aspeed_uart_routing *uart_routing = dev_get_drvdata(dev);
+	struct aspeed_uart_routing_selector *sel = to_routing_selector(attr);
+	int val, pos, len;
+
+	regmap_read(uart_routing->map, sel->reg, &val);
+	val = (val >> sel->shift) & sel->mask;
+
+	len = 0;
+	for (pos = 0; sel->options[pos] != NULL; ++pos) {
+		if (pos == val) {
+			len += snprintf(buf + len, PAGE_SIZE - 1 - len,
+					"[%s] ", sel->options[pos]);
+		} else {
+			len += snprintf(buf + len, PAGE_SIZE - 1 - len,
+					"%s ", sel->options[pos]);
+		}
+	}
+
+	if (val >= pos) {
+		len += snprintf(buf + len, PAGE_SIZE - 1 - len,
+				"[unknown(%d)]", val);
+	}
+
+	len += snprintf(buf + len, PAGE_SIZE - 1 - len, "\n");
+
+	return len;
+}
+
+static ssize_t aspeed_uart_routing_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count)
+{
+	unsigned long flags;
+	struct aspeed_uart_routing *uart_routing = dev_get_drvdata(dev);
+	struct aspeed_uart_routing_selector *sel = to_routing_selector(attr);
+	int val;
+
+	val = match_string(sel->options, -1, buf);
+	if (val < 0) {
+		dev_err(dev, "invalid value \"%s\"\n", buf);
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&uart_routing->lock, flags);
+
+	regmap_update_bits(uart_routing->map, sel->reg,
+			(sel->mask << sel->shift),
+			(val & sel->mask) << sel->shift);
+
+	spin_unlock_irqrestore(&uart_routing->lock, flags);
+
+	return count;
+}
+
+static int aspeed_uart_routing_probe(struct platform_device *pdev)
+{
+	int rc;
+	struct device *dev = &pdev->dev;
+	struct aspeed_uart_routing *uart_routing;
+
+	uart_routing = devm_kzalloc(&pdev->dev,
+				    sizeof(*uart_routing),
+				    GFP_KERNEL);
+	if (!uart_routing) {
+		dev_err(dev, "cannot allocate memory\n");
+		return -ENOMEM;
+	}
+
+	uart_routing->map = syscon_node_to_regmap(dev->parent->of_node);
+	if (IS_ERR(uart_routing->map)) {
+		dev_err(dev, "cannot get regmap\n");
+		return PTR_ERR(uart_routing->map);
+	}
+
+	uart_routing->attr_grp = of_device_get_match_data(dev);
+
+	spin_lock_init(&uart_routing->lock);
+
+	rc = sysfs_create_group(&dev->kobj,
+				uart_routing->attr_grp);
+	if (rc < 0)
+		return rc;
+
+	dev_set_drvdata(dev, uart_routing);
+
+	dev_info(dev, "module loaded\n");
+
+	return 0;
+}
+
+static int aspeed_uart_routing_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct aspeed_uart_routing *uart_routing = platform_get_drvdata(pdev);
+
+	sysfs_remove_group(&dev->kobj,
+			   uart_routing->attr_grp);
+
+	return 0;
+}
+
+static const struct of_device_id aspeed_uart_routing_table[] = {
+	{ .compatible = "aspeed,ast2500-lpc-uart-routing",
+	  .data = &ast2500_uart_routing_attr_group },
+	{ .compatible = "aspeed,ast2600-lpc-uart-routing",
+	  .data = &ast2600_uart_routing_attr_group },
+	{ },
+};
+
+static struct platform_driver aspeed_uart_routing_driver = {
+	.driver = {
+		.name = "aspeed-lpc-uart-routing",
+		.of_match_table = aspeed_uart_routing_table,
+	},
+	.probe = aspeed_uart_routing_probe,
+	.remove = aspeed_uart_routing_remove,
+};
+
+module_platform_driver(aspeed_uart_routing_driver);
+
+MODULE_AUTHOR("Oskar Senft <osk@google.com>");
+MODULE_AUTHOR("Chia-Wei Wang <chiawei_wang@aspeedtech.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Driver to configure Aspeed UART routing");