[PATCH 4/4] reset: add reset controller driver for SCMI agents

[Simon Glass]

Hi Etienne,

On Fri, 17 Jul 2020 at 09:43, Etienne Carriere
<etienne.carriere at linaro.org> wrote:
>
> This change introduces a reset controller driver for SCMI agent devices.
> When SCMI agent and SCMI reset domain drivers are enabled, SCMI agent
> binds a reset controller device for each SCMI reset domain protocol
> devices enabled in the FDT.
>
> SCMI reset driver is embedded upon CONFIG_RESET_SCMI=y. If enabled,
> CONFIG_SCMI_AGENT is also enabled.
>
> SCMI Reset Domain protocol is defined in the SCMI specification [1].
>
> Links: [1] https://developer.arm.com/architectures/system-architectures/software-standards/scmi
> Signed-off-by: Etienne Carriere <etienne.carriere at linaro.org>
> ---
>
>  drivers/firmware/scmi.c    |  3 ++
>  drivers/reset/Kconfig      |  8 ++++
>  drivers/reset/Makefile     |  1 +
>  drivers/reset/reset-scmi.c | 86 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 98 insertions(+)
>  create mode 100644 drivers/reset/reset-scmi.c

Reviewed-by: Simon Glass <sjg at chromium.org>

>
> diff --git a/drivers/firmware/scmi.c b/drivers/firmware/scmi.c
> index 9f06718df51..9be53a9cf11 100644
> --- a/drivers/firmware/scmi.c
> +++ b/drivers/firmware/scmi.c
> @@ -402,6 +402,9 @@ static int scmi_bind(struct udevice *dev)
>                 case SCMI_PROTOCOL_ID_CLOCK:
>                         drv = DM_GET_DRIVER(scmi_clock);
>                         break;
> +               case SCMI_PROTOCOL_ID_RESET_DOMAIN:
> +                       drv = DM_GET_DRIVER(scmi_reset_domain);
> +                       break;
>                 default:
>                         dev_info(dev, "Ignore unsupported SCMI protocol %u\n",
>                                  protocol_id);
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index 6d535612234..31bd4cd5b45 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -164,4 +164,12 @@ config RESET_RASPBERRYPI
>           relevant. This driver provides a reset controller capable of
>           interfacing with RPi4's co-processor and model these firmware
>           initialization routines as reset lines.
> +
> +config RESET_SCMI
> +       bool "Enable SCMI reset domain driver"
> +       select SCMI_FIRMWARE
> +       help
> +         Enable this option if you want to support reset controller
> +         devices exposed by a SCMI agent based on SCMI reset domain
> +         protocol communication with a SCMI server.
>  endmenu
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index 8e0124b8dee..f3c0fbfd8f3 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -25,3 +25,4 @@ obj-$(CONFIG_RESET_HISILICON) += reset-hisilicon.o
>  obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
>  obj-$(CONFIG_RESET_SYSCON) += reset-syscon.o
>  obj-$(CONFIG_RESET_RASPBERRYPI) += reset-raspberrypi.o
> +obj-$(CONFIG_RESET_SCMI) += reset-scmi.o
> diff --git a/drivers/reset/reset-scmi.c b/drivers/reset/reset-scmi.c
> new file mode 100644
> index 00000000000..e664d91d865
> --- /dev/null
> +++ b/drivers/reset/reset-scmi.c
> @@ -0,0 +1,86 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2019-2020 Linaro Limited
> + */
> +#include <common.h>
> +#include <dm.h>
> +#include <errno.h>
> +#include <reset-uclass.h>
> +#include <scmi.h>
> +#include <asm/types.h>
> +
> +enum scmi_reset_domain_message_id {
> +       SCMI_RESET_DOMAIN_RESET = 0x4,
> +};
> +
> +#define SCMI_RD_RESET_FLAG_ASSERT      BIT(1)
> +#define SCMI_RD_RESET_FLAG_DEASSERT    0
> +
> +struct scmi_rd_reset_in {
> +       u32 domain_id;
> +       u32 flags;
> +       u32 reset_state;
> +};
> +
> +struct scmi_rd_reset_out {
> +       s32 status;
> +};
> +
> +static int scmi_reset_set_state(struct reset_ctl *rst, int assert_not_deassert)
> +{
> +       struct scmi_rd_reset_in in = {
> +               .domain_id = rst->id,
> +               .flags = assert_not_deassert ? SCMI_RD_RESET_FLAG_ASSERT :
> +                        SCMI_RD_RESET_FLAG_DEASSERT,
> +               .reset_state = 0,
> +       };
> +       struct scmi_rd_reset_out out;
> +       struct scmi_msg scmi_msg = {
> +               .protocol_id = SCMI_PROTOCOL_ID_RESET_DOMAIN,
> +               .message_id = SCMI_RESET_DOMAIN_RESET,
> +               .in_msg = (u8 *)&in,
> +               .in_msg_sz = sizeof(in),
> +               .out_msg = (u8 *)&out,
> +               .out_msg_sz = sizeof(out),
> +       };
> +       int rc;
> +
> +       rc = scmi_send_and_process_msg(rst->dev->parent, &scmi_msg);
> +       if (rc)
> +               return rc;
> +
> +       return scmi_to_linux_errno(out.status);
> +}
> +
> +static int scmi_reset_assert(struct reset_ctl *rst)
> +{
> +       return scmi_reset_set_state(rst, SCMI_RD_RESET_FLAG_ASSERT);
> +}
> +
> +static int scmi_reset_deassert(struct reset_ctl *rst)
> +{
> +       return scmi_reset_set_state(rst, SCMI_RD_RESET_FLAG_DEASSERT);
> +}
> +
> +static int scmi_reset_request(struct reset_ctl *reset_ctl)
> +{

Do you actually need these two functions if they do nothing?

> +       return 0;
> +}
> +
> +static int scmi_reset_rfree(struct reset_ctl *reset_ctl)
> +{
> +       return 0;
> +}
> +
> +static const struct reset_ops scmi_reset_domain_ops = {
> +       .request        = scmi_reset_request,
> +       .rfree          = scmi_reset_rfree,
> +       .rst_assert     = scmi_reset_assert,
> +       .rst_deassert   = scmi_reset_deassert,
> +};
> +
> +U_BOOT_DRIVER(scmi_reset_domain) = {
> +       .name = "scmi_reset_domain",
> +       .id = UCLASS_RESET,
> +       .ops = &scmi_reset_domain_ops,
> +};
> --
> 2.17.1
>

Regards,
Simon