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To:     Lina Iyer <ilina@codeaurora.org>, andy.gross@linaro.org,
        david.brown@linaro.org, linux-arm-msm@vger.kernel.org,
        linux-soc@vger.kernel.org
From:   Stephen Boyd <swboyd@chromium.org>
In-Reply-To: <20180405161834.3850-2-ilina@codeaurora.org>
Cc:     rnayak@codeaurora.org, bjorn.andersson@linaro.org,
        linux-kernel@vger.kernel.org, evgreen@chromium.org,
        dianders@chromium.org, Lina Iyer <ilina@codeaurora.org>
References: <20180405161834.3850-1-ilina@codeaurora.org>
 <20180405161834.3850-2-ilina@codeaurora.org>
Message-ID: <152342153642.180276.4927130412537860735@swboyd.mtv.corp.google.com>
User-Agent: alot/0.7
Subject: Re: [PATCH v5 01/10] drivers: qcom: rpmh-rsc: add RPMH controller for QCOM
 SoCs
Date:   Tue, 10 Apr 2018 21:38:56 -0700
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Quoting Lina Iyer (2018-04-05 09:18:25)
> Add controller driver for QCOM SoCs that have hardware based shared
> resource management. The hardware IP known as RSC (Resource State
> Coordinator) houses multiple Direct Resource Voter (DRV) for different
> execution levels. A DRV is a unique voter on the state of a shared
> resource. A Trigger Control Set (TCS) is a bunch of slots that can house
> multiple resource state requests, that when triggered will issue those
> requests through an internal bus to the Resource Power Manager Hardened
> (RPMH) blocks. These hardware blocks are capable of adjusting clocks,
> voltages, etc. The resource state request from a DRV are aggregated along
> with state requests from other processors in the SoC and the aggregate
> value is applied on the resource.
> =

> Some important aspects of the RPMH communication -
> - Requests are <addr, value> with some header information
> - Multiple requests (upto 16) may be sent through a TCS, at a time
> - Requests in a TCS are sent in sequence
> - Requests may be fire-n-forget or completion (response expected)
> - Multiple TCS from the same DRV may be triggered simultaneously
> - Cannot send a request if another requesit for the same addr is in

s/requesit/request/

>   progress from the same DRV
> - When all the requests from a TCS are complete, an IRQ is raised
> - The IRQ handler needs to clear the TCS before it is available for
>   reuse
> - TCS configuration is specific to a DRV
> - Platform drivers may use DRV from different RSCs to make requests

This last point is sort of not true anymore? At least my understanding
is that platform drivers are children of the rsc and that they can only
use that rsc to do anything with rpmh.

> =

> Resource state requests made when CPUs are active are called 'active'
> state requests. Requests made when all the CPUs are powered down (idle
> state) are called 'sleep' state requests. They are matched by a
> corresponding 'wake' state requests which puts the resources back in to
> previously requested active state before resuming any CPU. TCSes are
> dedicated for each type of requests. Control TCS are used to provide
> specific information to the controller.

Can you mention AMC here too? I see the acronym but no definition of
what it is besides "Active or AMC" which may indicate A =3D=3D Active.

> =

> diff --git a/drivers/soc/qcom/rpmh-internal.h b/drivers/soc/qcom/rpmh-int=
ernal.h
> new file mode 100644
> index 000000000000..aa73ec4b3e42
> --- /dev/null
> +++ b/drivers/soc/qcom/rpmh-internal.h
> @@ -0,0 +1,89 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
> + */
> +
> +
> +#ifndef __RPM_INTERNAL_H__
> +#define __RPM_INTERNAL_H__
> +
> +#include <linux/bitmap.h>
> +#include <soc/qcom/tcs.h>
> +
> +#define TCS_TYPE_NR                    4
> +#define MAX_CMDS_PER_TCS               16
> +#define MAX_TCS_PER_TYPE               3
> +#define MAX_TCS_NR                     (MAX_TCS_PER_TYPE * TCS_TYPE_NR)
> +
> +struct rsc_drv;
> +
> +/**
> + * struct tcs_response: Response object for a request
> + *
> + * @drv:   the controller
> + * @msg:   the request for this response
> + * @m:     the tcs identifier
> + * @err:   error reported in the response
> + * @list:  element in list of pending response objects
> + */
> +struct tcs_response {
> +       struct rsc_drv *drv;
> +       const struct tcs_request *msg;
> +       u32 m;
> +       int err;
> +       struct list_head list;
> +};
> +
> +/**
> + * struct tcs_group: group of Trigger Command Sets for a request state

Put (ACRONYM) for the acronyms that are spelled out the first time
please. Also, make sure we know what 'request state' is.

> + *
> + * @drv:       the controller
> + * @type:      type of the TCS in this group - active, sleep, wake

Now 'group' means 'request state'?

> + * @mask:      mask of the TCSes relative to all the TCSes in the RSC
> + * @offset:    start of the TCS group relative to the TCSes in the RSC
> + * @num_tcs:   number of TCSes in this type
> + * @ncpt:      number of commands in each TCS
> + * @lock:      lock for synchronizing this TCS writes
> + * @responses: response objects for requests sent from each TCS
> + */
> +struct tcs_group {
> +       struct rsc_drv *drv;
> +       int type;

Is type supposed to be an enum?

> +       u32 mask;
> +       u32 offset;
> +       int num_tcs;
> +       int ncpt;
> +       spinlock_t lock;
> +       struct tcs_response *responses[MAX_TCS_PER_TYPE];
> +};
> +
> +/**
> + * struct rsc_drv: the Resource State Coordinator controller
> + *
> + * @name:       controller identifier
> + * @tcs_base:   start address of the TCS registers in this controller
> + * @id:         instance id in the controller (Direct Resource Voter)
> + * @num_tcs:    number of TCSes in this DRV

It changed from an RSC to a DRV here?

> + * @tasklet:    handle responses, off-load work from IRQ handler
> + * @response_pending:
> + *              list of responses that needs to be sent to caller
> + * @tcs:        TCS groups
> + * @tcs_in_use: s/w state of the TCS
> + * @drv_lock:  synchronize state of the controller
> + */
> +struct rsc_drv {

Is 'drv' in here talking about the DRV acronym?

> +       const char *name;
> +       void __iomem *tcs_base;
> +       int id;
> +       int num_tcs;
> +       struct tasklet_struct tasklet;
> +       struct list_head response_pending;
> +       struct tcs_group tcs[TCS_TYPE_NR];
> +       DECLARE_BITMAP(tcs_in_use, MAX_TCS_NR);
> +       spinlock_t drv_lock;

s/drv_lock/lock/

? Because otherwise it looks like drv->drv_lock.

> +};
> +
> +
> +int rpmh_rsc_send_data(struct rsc_drv *drv, const struct tcs_request *ms=
g);

Do we send data to anything else in rpmh? Maybe it could just be called
rpmh_send_data(), or rpmh_send().

> +
> +#endif /* __RPM_INTERNAL_H__ */
> diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
> new file mode 100644
> index 000000000000..8bde1e9bd599
> --- /dev/null
> +++ b/drivers/soc/qcom/rpmh-rsc.c
> @@ -0,0 +1,571 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
> + */
> +
> +#define pr_fmt(fmt) "%s " fmt, KBUILD_MODNAME
> +
> +#include <linux/atomic.h>

Is this used?

> +#include <linux/delay.h>
> +#include <linux/export.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/list.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +
> +#include <soc/qcom/tcs.h>
> +#include <dt-bindings/soc/qcom,rpmh-rsc.h>
> +
> +#include "rpmh-internal.h"
> +
> +#define RSC_DRV_TCS_OFFSET             672
> +#define RSC_DRV_CMD_OFFSET             20
> +
> +/* DRV Configuration Information Register */
> +#define DRV_PRNT_CHLD_CONFIG           0x0C
> +#define DRV_NUM_TCS_MASK               0x3F
> +#define DRV_NUM_TCS_SHIFT              6
> +#define DRV_NCPT_MASK                  0x1F
> +#define DRV_NCPT_SHIFT                 27
> +
> +/* Register offsets */
> +#define RSC_DRV_IRQ_ENABLE             0x00
> +#define RSC_DRV_IRQ_STATUS             0x04
> +#define RSC_DRV_IRQ_CLEAR              0x08
> +#define RSC_DRV_CMD_WAIT_FOR_CMPL      0x10
> +#define RSC_DRV_CONTROL                        0x14
> +#define RSC_DRV_STATUS                 0x18
> +#define RSC_DRV_CMD_ENABLE             0x1C
> +#define RSC_DRV_CMD_MSGID              0x30
> +#define RSC_DRV_CMD_ADDR               0x34
> +#define RSC_DRV_CMD_DATA               0x38
> +#define RSC_DRV_CMD_STATUS             0x3C
> +#define RSC_DRV_CMD_RESP_DATA          0x40
> +
> +#define TCS_AMC_MODE_ENABLE            BIT(16)
> +#define TCS_AMC_MODE_TRIGGER           BIT(24)
> +
> +/* TCS CMD register bit mask */
> +#define CMD_MSGID_LEN                  8
> +#define CMD_MSGID_RESP_REQ             BIT(8)
> +#define CMD_MSGID_WRITE                        BIT(16)
> +#define CMD_STATUS_ISSUED              BIT(8)
> +#define CMD_STATUS_COMPL               BIT(16)
> +
> +static struct tcs_group *get_tcs_from_index(struct rsc_drv *drv, int m)
> +{
> +       struct tcs_group *tcs;
> +       int i;
> +
> +       for (i =3D 0; i < drv->num_tcs; i++) {
> +               tcs =3D &drv->tcs[i];
> +               if (tcs->mask & BIT(m))
> +                       return tcs;
> +       }
> +
> +       WARN(i =3D=3D drv->num_tcs, "Incorrect TCS index %d", m);
> +
> +       return NULL;
> +}
> +
> +static struct tcs_response *setup_response(struct rsc_drv *drv,
> +                                          const struct tcs_request *msg,=
 int m)
> +{
> +       struct tcs_response *resp;
> +       struct tcs_group *tcs;
> +
> +       resp =3D kzalloc(sizeof(*resp), GFP_ATOMIC);
> +       if (!resp)
> +               return ERR_PTR(-ENOMEM);
> +
> +       resp->drv =3D drv;
> +       resp->msg =3D msg;
> +       resp->err =3D 0;
> +
> +       tcs =3D get_tcs_from_index(drv, m);
> +       if (!tcs)
> +               return ERR_PTR(-EINVAL);
> +
> +       assert_spin_locked(&tcs->lock);
> +       tcs->responses[m - tcs->offset] =3D resp;
> +
> +       return resp;
> +}
> +
> +static void free_response(struct tcs_response *resp)

const?

> +{
> +       kfree(resp);
> +}
> +
> +static struct tcs_response *get_response(struct rsc_drv *drv, u32 m)
> +{
> +       struct tcs_group *tcs =3D get_tcs_from_index(drv, m);
> +
> +       return tcs->responses[m - tcs->offset];
> +}
> +
> +static u32 read_tcs_reg(struct rsc_drv *drv, int reg, int m, int n)
> +{
> +       return readl_relaxed(drv->tcs_base + reg + RSC_DRV_TCS_OFFSET * m=
 +
> +                            RSC_DRV_CMD_OFFSET * n);
> +}
> +
> +static void write_tcs_reg(struct rsc_drv *drv, int reg, int m, int n, u3=
2 data)

Is m the type of TCS (sleep, active, wake) and n is just an offset?
Maybe you can replace m with 'tcs_type' and n with 'index' or 'i' or
'offset'. And then don't use this function to write the random TCS
registers that don't have to do with the TCS command slots? I see
various places where there are things like:

> +               write_tcs_reg(drv, RSC_DRV_CMD_ENABLE, m, 0, 0);
> +       write_tcs_reg(drv, RSC_DRV_CMD_WAIT_FOR_CMPL, m, 0, cmd_complete);
> +       write_tcs_reg(drv, RSC_DRV_CMD_ENABLE, m, 0, cmd_enable);

And 'n' is 0, meaning you rely on that 0 killing that last part of the
equation (RSC_DRV_CMD_OFFSET * n). But if we had a write_tcs_reg(drv,
reg, m, data) and a write_tcs_cmd(drv, reg, m, n, data) then it would be
clearer.

Even better, add a void *base to a 'struct tcs' and then pass that
struct to the tcs_read/write APIs and then have that pull out a
tcs->base + reg or tcs->base + reg + RSC_DRV_CMD_OFFSET * index.

> +{
> +       writel_relaxed(data, drv->tcs_base + reg + RSC_DRV_TCS_OFFSET * m=
 +
> +                      RSC_DRV_CMD_OFFSET * n);
> +}
> +
> +static void write_tcs_reg_sync(struct rsc_drv *drv, int reg, int m, int =
n,
> +                              u32 data)
> +{
> +       write_tcs_reg(drv, reg, m, n, data);
> +       for (;;) {
> +               if (data =3D=3D read_tcs_reg(drv, reg, m, n))
> +                       break;
> +               udelay(1);
> +       }
> +}
> +
> +static bool tcs_is_free(struct rsc_drv *drv, int m)
> +{
> +       return !test_bit(m, drv->tcs_in_use) &&
> +              read_tcs_reg(drv, RSC_DRV_STATUS, m, 0);
> +}
> +
> +static struct tcs_group *get_tcs_of_type(struct rsc_drv *drv, int type)
> +{
> +       int i;
> +       struct tcs_group *tcs;
> +
> +       for (i =3D 0; i < TCS_TYPE_NR; i++) {
> +               if (type =3D=3D drv->tcs[i].type)
> +                       break;
> +       }
> +
> +       if (i =3D=3D TCS_TYPE_NR)
> +               return ERR_PTR(-EINVAL);
> +
> +       tcs =3D &drv->tcs[i];
> +       if (!tcs->num_tcs)
> +               return ERR_PTR(-EINVAL);
> +
> +       return tcs;
> +}
> +
> +static struct tcs_group *get_tcs_for_msg(struct rsc_drv *drv,
> +                                        const struct tcs_request *msg)
> +{
> +       int type;
> +
> +       switch (msg->state) {
> +       case RPMH_ACTIVE_ONLY_STATE:
> +               type =3D ACTIVE_TCS;
> +               break;
> +       default:
> +               return ERR_PTR(-EINVAL);
> +       }
> +
> +       return get_tcs_of_type(drv, type);
> +}
> +
> +static void send_tcs_response(struct tcs_response *resp)
> +{
> +       struct rsc_drv *drv;
> +       unsigned long flags;
> +
> +       if (!resp)
> +               return;

Sad.

> +
> +       drv =3D resp->drv;
> +       spin_lock_irqsave(&drv->drv_lock, flags);
> +       INIT_LIST_HEAD(&resp->list);
> +       list_add_tail(&resp->list, &drv->response_pending);
> +       spin_unlock_irqrestore(&drv->drv_lock, flags);
> +
> +       tasklet_schedule(&drv->tasklet);
> +}
> +
> +/**
> + * tcs_irq_handler: TX Done interrupt handler

So call it tcs_tx_done?

> + */
> +static irqreturn_t tcs_irq_handler(int irq, void *p)
> +{
> +       struct rsc_drv *drv =3D p;
> +       int m, i;
> +       u32 irq_status, sts;
> +       struct tcs_response *resp;
> +       struct tcs_cmd *cmd;
> +
> +       irq_status =3D read_tcs_reg(drv, RSC_DRV_IRQ_STATUS, 0, 0);
> +
> +       for (m =3D 0; m < drv->num_tcs; m++) {
> +               if (!(irq_status & (u32)BIT(m)))
> +                       continue;
> +
> +               resp =3D get_response(drv, m);
> +               if (WARN_ON(!resp))
> +                       goto skip_resp;
> +
> +               resp->err =3D 0;
> +               for (i =3D 0; i < resp->msg->num_cmds; i++) {
> +                       cmd =3D &resp->msg->cmds[i];
> +                       sts =3D read_tcs_reg(drv, RSC_DRV_CMD_STATUS, m, =
i);
> +                       if (!(sts & CMD_STATUS_ISSUED) ||
> +                          ((resp->msg->wait_for_compl || cmd->wait) &&
> +                          !(sts & CMD_STATUS_COMPL))) {
> +                               resp->err =3D -EIO;
> +                               break;
> +                       }
> +               }
> +skip_resp:
> +               /* Reclaim the TCS */
> +               write_tcs_reg(drv, RSC_DRV_CMD_ENABLE, m, 0, 0);
> +               write_tcs_reg(drv, RSC_DRV_IRQ_CLEAR, 0, 0, BIT(m));
> +               clear_bit(m, drv->tcs_in_use);

Should we reclaim the TCS if the above for loop fails too? It may make
more sense to look up the response, reclaim, check if it's NULL and
execute a 'continue' and otherwise look through resp->msg->cmds for
something that was done and then send_tcs_response(). At the least,
don't call send_tcs_response() if resp =3D=3D NULL.

> +               send_tcs_response(resp);
> +       }
> +
> +       return IRQ_HANDLED;
> +}
> +
> +/**
> + * tcs_notify_tx_done: TX Done for requests that got a response
> + *
> + * @data: the tasklet argument
> + *
> + * Tasklet function to notify MBOX that we are done with the request.
> + * Handles all pending reponses whenever run.
> + */
> +static void tcs_notify_tx_done(unsigned long data)
> +{
> +       struct rsc_drv *drv =3D (struct rsc_drv *)data;
> +       struct tcs_response *resp;
> +       unsigned long flags;
> +
> +       for (;;) {
> +               spin_lock_irqsave(&drv->drv_lock, flags);
> +               resp =3D list_first_entry_or_null(&drv->response_pending,
> +                                               struct tcs_response, list=
);
> +               if (!resp) {
> +                       spin_unlock_irqrestore(&drv->drv_lock, flags);
> +                       break;
> +               }
> +               list_del(&resp->list);

Someone should make a list_deqeue() API. Then this would read as:

		spin_lock_irqsave()
		resp =3D list_deqeue();
		spin_unlock_irqrestore()
		if (!resp)
			break;
		free_response(resp)

> +               spin_unlock_irqrestore(&drv->drv_lock, flags);
> +               free_response(resp);
> +       }
> +}
> +
> +static void __tcs_buffer_write(struct rsc_drv *drv, int m, int n,
> +                              const struct tcs_request *msg)
> +{
> +       u32 msgid, cmd_msgid;
> +       u32 cmd_enable =3D 0;
> +       u32 cmd_complete;
> +       struct tcs_cmd *cmd;
> +       int i, j;
> +
> +       cmd_msgid =3D CMD_MSGID_LEN;
> +       cmd_msgid |=3D msg->wait_for_compl ? CMD_MSGID_RESP_REQ : 0;
> +       cmd_msgid |=3D CMD_MSGID_WRITE;
> +
> +       cmd_complete =3D read_tcs_reg(drv, RSC_DRV_CMD_WAIT_FOR_CMPL, m, =
0);
> +
> +       for (i =3D 0, j =3D n; i < msg->num_cmds; i++, j++) {
> +               cmd =3D &msg->cmds[i];
> +               cmd_enable |=3D BIT(j);
> +               cmd_complete |=3D cmd->wait << j;
> +               msgid =3D cmd_msgid;
> +               msgid |=3D cmd->wait ? CMD_MSGID_RESP_REQ : 0;
> +               write_tcs_reg(drv, RSC_DRV_CMD_MSGID, m, j, msgid);
> +               write_tcs_reg(drv, RSC_DRV_CMD_ADDR, m, j, cmd->addr);
> +               write_tcs_reg(drv, RSC_DRV_CMD_DATA, m, j, cmd->data);
> +       }
> +
> +       write_tcs_reg(drv, RSC_DRV_CMD_WAIT_FOR_CMPL, m, 0, cmd_complete);
> +       cmd_enable |=3D read_tcs_reg(drv, RSC_DRV_CMD_ENABLE, m, 0);
> +       write_tcs_reg(drv, RSC_DRV_CMD_ENABLE, m, 0, cmd_enable);
> +}
> +
> +static void __tcs_trigger(struct rsc_drv *drv, int m)
> +{
> +       u32 enable;
> +
> +       /*
> +        * HW req: Clear the DRV_CONTROL and enable TCS again
> +        * While clearing ensure that the AMC mode trigger is cleared
> +        * and then the mode enable is cleared.
> +        */
> +       enable =3D read_tcs_reg(drv, RSC_DRV_CONTROL, m, 0);
> +       enable &=3D ~TCS_AMC_MODE_TRIGGER;
> +       write_tcs_reg_sync(drv, RSC_DRV_CONTROL, m, 0, enable);
> +       enable &=3D ~TCS_AMC_MODE_ENABLE;
> +       write_tcs_reg_sync(drv, RSC_DRV_CONTROL, m, 0, enable);
> +
> +       /* Enable the AMC mode on the TCS and then trigger the TCS */
> +       enable =3D TCS_AMC_MODE_ENABLE;
> +       write_tcs_reg_sync(drv, RSC_DRV_CONTROL, m, 0, enable);
> +       enable |=3D TCS_AMC_MODE_TRIGGER;
> +       write_tcs_reg_sync(drv, RSC_DRV_CONTROL, m, 0, enable);
> +}
> +
> +static int check_for_req_inflight(struct rsc_drv *drv, struct tcs_group =
*tcs,
> +                                 const struct tcs_request *msg)
> +{
> +       unsigned long curr_enabled;
> +       u32 addr;
> +       int i, j, k;
> +       int m =3D tcs->offset;
> +
> +       for (i =3D 0; i < tcs->num_tcs; i++, m++) {
> +               if (tcs_is_free(drv, m))
> +                       continue;
> +
> +               curr_enabled =3D read_tcs_reg(drv, RSC_DRV_CMD_ENABLE, m,=
 0);
> +
> +               for_each_set_bit(j, &curr_enabled, MAX_CMDS_PER_TCS) {
> +                       addr =3D read_tcs_reg(drv, RSC_DRV_CMD_ADDR, m, j=
);
> +                       for (k =3D 0; k < msg->num_cmds; k++) {
> +                               if (addr =3D=3D msg->cmds[k].addr)
> +                                       return -EBUSY;
> +                       }
> +               }
> +       }
> +
> +       return 0;
> +}
> +
> +static int find_free_tcs(struct tcs_group *tcs)
> +{
> +       int m;
> +
> +       for (m =3D 0; m < tcs->num_tcs; m++) {
> +               if (tcs_is_free(tcs->drv, tcs->offset + m))
> +                       return m;
> +       }
> +
> +       return -EBUSY;
> +}
> +
> +static int tcs_mbox_write(struct rsc_drv *drv, const struct tcs_request =
*msg)
> +{
> +       struct tcs_group *tcs;
> +       int m;
> +       struct tcs_response *resp =3D NULL;
> +       unsigned long flags;
> +       int ret;
> +
> +       tcs =3D get_tcs_for_msg(drv, msg);
> +       if (IS_ERR(tcs))
> +               return PTR_ERR(tcs);
> +
> +       spin_lock_irqsave(&tcs->lock, flags);
> +       m =3D find_free_tcs(tcs);
> +       if (m < 0) {
> +               ret =3D m;
> +               goto done_write;
> +       }
> +
> +       /*
> +        * The h/w does not like if we send a request to the same address,
> +        * when one is already in-flight or being processed.
> +        */
> +       ret =3D check_for_req_inflight(drv, tcs, msg);
> +       if (ret)
> +               goto done_write;
> +
> +       resp =3D setup_response(drv, msg, m);
> +       if (IS_ERR(resp)) {
> +               ret =3D PTR_ERR(resp);
> +               goto done_write;
> +       }
> +       resp->m =3D m;
> +
> +       set_bit(m, drv->tcs_in_use);
> +       __tcs_buffer_write(drv, m, 0, msg);
> +       __tcs_trigger(drv, m);
> +
> +done_write:
> +       spin_unlock_irqrestore(&tcs->lock, flags);
> +       return ret;
> +}
> +
> +/**
> + * rpmh_rsc_send_data: Validate the incoming message and write to the
> + * appropriate TCS block.
> + *
> + * @drv: the controller
> + * @msg: the data to be sent
> + *
> + * Return: 0 on success, -EINVAL on error.
> + * Note: This call blocks until a valid data is written to the TCS.
> + */
> +int rpmh_rsc_send_data(struct rsc_drv *drv, const struct tcs_request *ms=
g)
> +{
> +       int ret;
> +
> +       if (!msg || !msg->cmds || !msg->num_cmds ||
> +           msg->num_cmds > MAX_RPMH_PAYLOAD)
> +               return -EINVAL;
> +
> +       do {
> +               ret =3D tcs_mbox_write(drv, msg);
> +               if (ret =3D=3D -EBUSY) {
> +                       pr_info_ratelimited("TCS Busy, retrying RPMH mess=
age send: addr=3D%#x\n",
> +                                           msg->cmds[0].addr);
> +                       udelay(10);
> +               }
> +       } while (ret =3D=3D -EBUSY);

This loop never breaks if we can't avoid the BUSY loop. And that printk
is informational, shouldn't it be an error? Is there some number of
tries we can make and then just give up?

> +
> +       return ret;
> +}
> +EXPORT_SYMBOL(rpmh_rsc_send_data);
> +
> +static int rpmh_probe_tcs_config(struct platform_device *pdev,
> +                                struct rsc_drv *drv)
> +{
> +       struct tcs_type_config {
> +               u32 type;
> +               u32 n;
> +       } tcs_cfg[TCS_TYPE_NR] =3D { { 0 } };
> +       struct device_node *dn =3D pdev->dev.of_node;
> +       u32 config, max_tcs, ncpt;
> +       int i, ret, n, st =3D 0;
> +       struct tcs_group *tcs;
> +       struct resource *res;
> +       void __iomem *base;
> +
> +       res =3D platform_get_resource_byname(pdev, IORESOURCE_MEM, "drv");
> +       base =3D devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(base))
> +               return PTR_ERR(base);
> +
> +       res =3D platform_get_resource_byname(pdev, IORESOURCE_MEM, "tcs");
> +       drv->tcs_base =3D devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(drv->tcs_base))
> +               return PTR_ERR(drv->tcs_base);
> +
> +       config =3D readl_relaxed(base + DRV_PRNT_CHLD_CONFIG);
> +
> +       max_tcs =3D config;
> +       max_tcs &=3D DRV_NUM_TCS_MASK << (DRV_NUM_TCS_SHIFT * drv->id);
> +       max_tcs =3D max_tcs >> (DRV_NUM_TCS_SHIFT * drv->id);
> +
> +       ncpt =3D config & (DRV_NCPT_MASK << DRV_NCPT_SHIFT);
> +       ncpt =3D ncpt >> DRV_NCPT_SHIFT;
> +
> +       n =3D of_property_count_u32_elems(dn, "qcom,tcs-config");
> +       if (n !=3D 2 * TCS_TYPE_NR)
> +               return -EINVAL;
> +
> +       for (i =3D 0; i < TCS_TYPE_NR; i++) {
> +               ret =3D of_property_read_u32_index(dn, "qcom,tcs-config",
> +                                                i * 2, &tcs_cfg[i].type);
> +               if (ret)
> +                       return ret;
> +               if (tcs_cfg[i].type >=3D TCS_TYPE_NR)
> +                       return -EINVAL;
> +
> +               ret =3D of_property_read_u32_index(dn, "qcom,tcs-config",
> +                                                i * 2 + 1, &tcs_cfg[i].n=
);
> +               if (ret)
> +                       return ret;
> +               if (tcs_cfg[i].n > MAX_TCS_PER_TYPE)
> +                       return -EINVAL;
> +       }
> +
> +       for (i =3D 0; i < TCS_TYPE_NR; i++) {
> +               tcs =3D &drv->tcs[tcs_cfg[i].type];
> +               if (tcs->drv)
> +                       return -EINVAL;
> +               tcs->drv =3D drv;
> +               tcs->type =3D tcs_cfg[i].type;
> +               tcs->num_tcs =3D tcs_cfg[i].n;
> +               tcs->ncpt =3D ncpt;
> +               spin_lock_init(&tcs->lock);
> +
> +               if (!tcs->num_tcs || tcs->type =3D=3D CONTROL_TCS)
> +                       continue;
> +
> +               if (st + tcs->num_tcs > max_tcs ||
> +                   st + tcs->num_tcs >=3D BITS_PER_BYTE * sizeof(tcs->ma=
sk))
> +                       return -EINVAL;
> +
> +               tcs->mask =3D ((1 << tcs->num_tcs) - 1) << st;
> +               tcs->offset =3D st;
> +               st +=3D tcs->num_tcs;
> +       }
> +
> +       drv->num_tcs =3D st;
> +
> +       return 0;
> +}
> +
> +static int rpmh_rsc_probe(struct platform_device *pdev)
> +{
> +       struct device_node *dn =3D pdev->dev.of_node;
> +       struct rsc_drv *drv;
> +       int ret, irq;
> +
> +       drv =3D devm_kzalloc(&pdev->dev, sizeof(*drv), GFP_KERNEL);
> +       if (!drv)
> +               return -ENOMEM;
> +
> +       ret =3D of_property_read_u32(dn, "qcom,drv-id", &drv->id);
> +       if (ret)
> +               return ret;
> +
> +       drv->name =3D of_get_property(dn, "label", NULL);
> +       if (!drv->name)
> +               drv->name =3D dev_name(&pdev->dev);
> +
> +       ret =3D rpmh_probe_tcs_config(pdev, drv);
> +       if (ret)
> +               return ret;
> +
> +       INIT_LIST_HEAD(&drv->response_pending);
> +       spin_lock_init(&drv->drv_lock);
> +       tasklet_init(&drv->tasklet, tcs_notify_tx_done, (unsigned long)dr=
v);
> +       bitmap_zero(drv->tcs_in_use, MAX_TCS_NR);
> +
> +       irq =3D platform_get_irq(pdev, 0);
> +       if (irq < 0)
> +               return irq;
> +
> +       ret =3D devm_request_irq(&pdev->dev, irq, tcs_irq_handler,
> +                              IRQF_TRIGGER_HIGH | IRQF_NO_SUSPEND,
> +                              drv->name, drv);
> +       if (ret)
> +               return ret;
> +
> +       /* Enable the active TCS to send requests immediately */
> +       write_tcs_reg(drv, RSC_DRV_IRQ_ENABLE, 0, 0, drv->tcs[ACTIVE_TCS]=
.mask);
> +
> +       return devm_of_platform_populate(&pdev->dev);
> +}
> +
> diff --git a/include/dt-bindings/soc/qcom,rpmh-rsc.h b/include/dt-binding=
s/soc/qcom,rpmh-rsc.h
> new file mode 100644
> index 000000000000..868f998ea998
> --- /dev/null
> +++ b/include/dt-bindings/soc/qcom,rpmh-rsc.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
> + */
> +
> +#ifndef __DT_QCOM_RPMH_RSC_H__
> +#define __DT_QCOM_RPMH_RSC_H__
> +
> +#define SLEEP_TCS      0
> +#define WAKE_TCS       1
> +#define ACTIVE_TCS     2
> +#define CONTROL_TCS    3

Is anything besides the RSC node going to use these defines? Typically
we have defines for things that are used by many nodes in many places
and also in C code by drivers so this looks odd if it's mostly used for
packing many properties into a single property on the DT side.

> +
> +#endif /* __DT_QCOM_RPMH_RSC_H__ */
> diff --git a/include/soc/qcom/tcs.h b/include/soc/qcom/tcs.h
> new file mode 100644
> index 000000000000..4b78f881010a
> --- /dev/null
> +++ b/include/soc/qcom/tcs.h
> @@ -0,0 +1,56 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
> + */
> +
> +#ifndef __SOC_QCOM_TCS_H__
> +#define __SOC_QCOM_TCS_H__
> +
> +#define MAX_RPMH_PAYLOAD       16
> +
> +/**
> + * rpmh_state: state for the request
> + *
> + * RPMH_SLEEP_STATE:       State of the resource when the processor subs=
ystem
> + *                         is powered down. There is no client using the
> + *                         resource actively.
> + * RPMH_WAKE_ONLY_STATE:   Resume resource state to the value previously
> + *                         requested before the processor was powered do=
wn.
> + * RPMH_ACTIVE_ONLY_STATE: Active or AMC mode requests. Resource state
> + *                         is aggregated immediately.
> + */
> +enum rpmh_state {
> +       RPMH_SLEEP_STATE,
> +       RPMH_WAKE_ONLY_STATE,
> +       RPMH_ACTIVE_ONLY_STATE,
> +};
> +
> +/**
> + * struct tcs_cmd: an individual request to RPMH.
> + *
> + * @addr: the address of the resource slv_id:18:16 | offset:0:15
> + * @data: the resource state request
> + * @wait: wait for this request to be complete before sending the next
> + */
> +struct tcs_cmd {
> +       u32 addr;
> +       u32 data;
> +       bool wait;
> +};
> +
> +/**
> + * struct tcs_request: A set of tcs_cmds sent together in a TCS
> + *
> + * @state:          state for the request.

Drop full stop please

> + * @wait_for_compl: wait until we get a response from the h/w accelerator
> + * @num_cmds:       the number of @cmds in this request
> + * @cmds:           an array of tcs_cmds
> + */
> +struct tcs_request {
> +       enum rpmh_state state;
> +       bool wait_for_compl;
> +       u32 num_cmds;
> +       struct tcs_cmd *cmds;
> +};