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References: <20210927023053.6728-1-chiawei_wang@aspeedtech.com>
 <20210927023053.6728-5-chiawei_wang@aspeedtech.com>
In-Reply-To: <20210927023053.6728-5-chiawei_wang@aspeedtech.com>
From: Joel Stanley <joel@jms.id.au>
Date: Fri, 8 Oct 2021 04:47:23 +0000
Message-ID: <CACPK8XdLgF4mA5iLjZQMK8JpGmr=3YJ4GAPM5U5f7LG=VEAe+Q@mail.gmail.com>
Subject: Re: [PATCH v7 4/5] soc: aspeed: Add UART routing support
To: Chia-Wei Wang <chiawei_wang@aspeedtech.com>, Arnd Bergmann <arnd@arndb.de>
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Cc: devicetree <devicetree@vger.kernel.org>,
 linux-aspeed <linux-aspeed@lists.ozlabs.org>, Andrew Jeffery <andrew@aj.id.au>,
 OpenBMC Maillist <openbmc@lists.ozlabs.org>,
 Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
 Rob Herring <robh+dt@kernel.org>, Oskar Senft <osk@google.com>,
 Linux ARM <linux-arm-kernel@lists.infradead.org>
Errors-To: openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org
Sender: "openbmc"
 <openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org>

Hi Arnd,

On Mon, 27 Sept 2021 at 02:31, Chia-Wei Wang
<chiawei_wang@aspeedtech.com> wrote:
>
> Add driver support for the UART routing control. Users can perform
> runtime configuration of the RX muxes among the UART controllers and
> the UART IO pins.
>
> The sysfs interface is also exported for the convenience of routing paths
> check and update.

I would like you to take a look at this one before I put it in the
aspeed tree for v5.16.

This is a BMC specific function, and it's quite specific to the way
the Aspeed part works. I am not a huge fan of the sysfs interface, but
I don't have a better suggestion.

The configuration needs to be runtime, as some systems change where
the serial output appears based on a user connecting to the BMC.

Cheers,

Joel

>
> Signed-off-by: Oskar Senft <osk@google.com>
> Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
> Tested-by: Lei YU <yulei.sh@bytedance.com>
> ---
>  .../testing/sysfs-driver-aspeed-uart-routing  |  27 +
>  drivers/soc/aspeed/Kconfig                    |  10 +
>  drivers/soc/aspeed/Makefile                   |   9 +-
>  drivers/soc/aspeed/aspeed-uart-routing.c      | 603 ++++++++++++++++++
>  4 files changed, 645 insertions(+), 4 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-driver-aspeed-uart-routing
>  create mode 100644 drivers/soc/aspeed/aspeed-uart-routing.c
>
> diff --git a/Documentation/ABI/testing/sysfs-driver-aspeed-uart-routing b/Documentation/ABI/testing/sysfs-driver-aspeed-uart-routing
> new file mode 100644
> index 000000000000..b363827da437
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-driver-aspeed-uart-routing
> @@ -0,0 +1,27 @@
> +What:          /sys/bus/platform/drivers/aspeed-uart-routing/*/uart*
> +Date:          September 2021
> +Contact:       Oskar Senft <osk@google.com>
> +               Chia-Wei Wang <chiawei_wang@aspeedtech.com>
> +Description:   Selects the RX source of the UARTx device.
> +
> +               When read, each file shows the list of available options with currently
> +               selected option marked by brackets "[]". The list of available options
> +               depends on the selected file.
> +
> +               e.g.
> +               cat /sys/bus/platform/drivers/aspeed-uart-routing/*.uart_routing/uart1
> +               [io1] io2 io3 io4 uart2 uart3 uart4 io6
> +
> +               In this case, UART1 gets its input from IO1 (physical serial port 1).
> +
> +Users:         OpenBMC.  Proposed changes should be mailed to
> +               openbmc@lists.ozlabs.org
> +
> +What:          /sys/bus/platform/drivers/aspeed-uart-routing/*/io*
> +Date:          September 2021
> +Contact:       Oskar Senft <osk@google.com>
> +               Chia-Wei Wang <chiawei_wang@aspeedtech.com>
> +Description:   Selects the RX source of IOx serial port. The current selection
> +               will be marked by brackets "[]".
> +Users:         OpenBMC.  Proposed changes should be mailed to
> +               openbmc@lists.ozlabs.org
> diff --git a/drivers/soc/aspeed/Kconfig b/drivers/soc/aspeed/Kconfig
> index 243ca196e6ad..f579ee0b5afa 100644
> --- a/drivers/soc/aspeed/Kconfig
> +++ b/drivers/soc/aspeed/Kconfig
> @@ -24,6 +24,16 @@ 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_UART_ROUTING
> +       tristate "ASPEED uart routing control"
> +       select REGMAP
> +       select MFD_SYSCON
> +       default ARCH_ASPEED
> +       help
> +         Provides a driver to control the UART routing paths, allowing
> +         users to perform runtime configuration of the RX muxes among
> +         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..b35d74592964 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-$(CONFIG_ASPEED_UART_ROUTING)      += aspeed-uart-routing.o
> +obj-$(CONFIG_ASPEED_P2A_CTRL)          += aspeed-p2a-ctrl.o
> +obj-$(CONFIG_ASPEED_SOCINFO)           += aspeed-socinfo.o
> diff --git a/drivers/soc/aspeed/aspeed-uart-routing.c b/drivers/soc/aspeed/aspeed-uart-routing.c
> new file mode 100644
> index 000000000000..ef8b24fd1851
> --- /dev/null
> +++ b/drivers/soc/aspeed/aspeed-uart-routing.c
> @@ -0,0 +1,603 @@
> +// 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_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;
> +       struct attribute_group const *attr_grp;
> +};
> +
> +struct aspeed_uart_routing_selector {
> +       struct device_attribute dev_attr;
> +       uint8_t reg;
> +       uint8_t mask;
> +       uint8_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 += sysfs_emit_at(buf, len, "[%s] ", sel->options[pos]);
> +               else
> +                       len += sysfs_emit_at(buf, len, "%s ", sel->options[pos]);
> +       }
> +
> +       if (val >= pos)
> +               len += sysfs_emit_at(buf, len, "[unknown(%d)]", val);
> +
> +       len += sysfs_emit_at(buf, len, "\n");
> +
> +       return len;
> +}
> +
> +static ssize_t aspeed_uart_routing_store(struct device *dev,
> +                                        struct device_attribute *attr,
> +                                        const char *buf, size_t count)
> +{
> +       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;
> +       }
> +
> +       regmap_update_bits(uart_routing->map, sel->reg,
> +                       (sel->mask << sel->shift),
> +                       (val & sel->mask) << sel->shift);
> +
> +       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)
> +               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);
> +
> +       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,ast2400-uart-routing",
> +         .data = &ast2500_uart_routing_attr_group },
> +       { .compatible = "aspeed,ast2500-uart-routing",
> +         .data = &ast2500_uart_routing_attr_group },
> +       { .compatible = "aspeed,ast2600-uart-routing",
> +         .data = &ast2600_uart_routing_attr_group },
> +       { },
> +};
> +
> +static struct platform_driver aspeed_uart_routing_driver = {
> +       .driver = {
> +               .name = "aspeed-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");
> --
> 2.17.1
>