linux-kernel - Re: [PATCH v3 2/4] drivers: firmware: xilinx: Add ZynqMP firmware driver

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Date:   Tue, 30 Jan 2018 10:35:52 +0530
From:   Shubhrajyoti Datta <shubhrajyoti.datta@...il.com>
To:     Jolly Shah <jolly.shah@...inx.com>
Cc:     ard.biesheuvel@...aro.org, mingo@...nel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        matt@...eblueprint.co.uk, sudeep.holla@....com,
        hkallweit1@...il.com, keescook@...omium.org,
        dmitry.torokhov@...il.com, Michal Simek <michal.simek@...inx.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, Jolly Shah <jollys@...inx.com>,
        Rajan Vaja <rajanv@...inx.com>
Subject: Re: [PATCH v3 2/4] drivers: firmware: xilinx: Add ZynqMP firmware driver

Hi,

Thanks for the patch.
A few questions below.


On Thu, Jan 25, 2018 at 4:51 AM, Jolly Shah <jolly.shah@...inx.com> wrote:
> This patch is adding communication layer with firmware.
> Firmware driver provides an interface to firmware APIs.
> Interface APIs can be used by any driver to communicate to
> PMUFW(Platform Management Unit). All requests go through ATF.
>
> Signed-off-by: Jolly Shah <jollys@...inx.com>
> Signed-off-by: Rajan Vaja <rajanv@...inx.com>
> ---
<snip>
>

> +/**
> + * zynqmp_pm_clock_enable - Enable the clock for given id
> + * @clock_id:  ID of the clock to be enabled

Does it enable all the parents also if they are disabled?

> + *
> + * This function is used by master to enable the clock
> + * including peripherals and PLL clocks.
> + *
> + * Return:     Returns status, either success or error+reason.
> + */
> +static int zynqmp_pm_clock_enable(u32 clock_id)
> +{
> +       return invoke_pm_fn(PM_CLOCK_ENABLE, clock_id, 0, 0, 0, NULL);
> +}
> +
> +/**
> + * zynqmp_pm_clock_disable - Disable the clock for given id
> + * @clock_id:  ID of the clock to be disable
> + *
> + * This function is used by master to disable the clock
> + * including peripherals and PLL clocks.
> + *
> + * Return:     Returns status, either success or error+reason.
> + */
> +static int zynqmp_pm_clock_disable(u32 clock_id)
> +{
> +       return invoke_pm_fn(PM_CLOCK_DISABLE, clock_id, 0, 0, 0, NULL);
> +}
> +
> +/**
> + * zynqmp_pm_clock_getstate - Get the clock state for given id
> + * @clock_id:  ID of the clock to be queried
> + * @state:     1/0 (Enabled/Disabled)
> + *
> + * This function is used by master to get the state of clock
> + * including peripherals and PLL clocks.
> + *
> + * Return:     Returns status, either success or error+reason.
> + */
> +static int zynqmp_pm_clock_getstate(u32 clock_id, u32 *state)
> +{
> +       u32 ret_payload[PAYLOAD_ARG_CNT];
> +       int ret;
> +
> +       ret = invoke_pm_fn(PM_CLOCK_GETSTATE, clock_id, 0, 0, 0, ret_payload);
> +       *state = ret_payload[1];
> +
> +       return ret;
> +}
> +
> +/**
> + * zynqmp_pm_clock_setdivider - Set the clock divider for given id
> + * @clock_id:  ID of the clock
> + * @div_type:  TYPE_DIV1: div1
> + *             TYPE_DIV2: div2
div type didnt see in the signature.



> + * @divider:   divider value.
> + *
> + * This function is used by master to set divider for any clock
> + * to achieve desired rate.
> + *
> + * Return:     Returns status, either success or error+reason.
> + */
> +static int zynqmp_pm_clock_setdivider(u32 clock_id, u32 divider)
> +{
> +       return invoke_pm_fn(PM_CLOCK_SETDIVIDER, clock_id, divider, 0, 0, NULL);
> +}
> +
> +/**
> + * zynqmp_pm_clock_getdivider - Get the clock divider for given id
> + * @clock_id:  ID of the clock
> + * @div_type:  TYPE_DIV1: div1
> + *             TYPE_DIV2: div2
didnt see this  below.

> + * @divider:   divider value.
> + *
> + * This function is used by master to get divider values
> + * for any clock.
> + *
> + * Return:     Returns status, either success or error+reason.
> + */
> +static int zynqmp_pm_clock_getdivider(u32 clock_id, u32 *divider)
> +{
> +       u32 ret_payload[PAYLOAD_ARG_CNT];
> +       int ret;
> +
> +       ret = invoke_pm_fn(PM_CLOCK_GETDIVIDER, clock_id, 0, 0, 0, ret_payload);
> +       *divider = ret_payload[1];
> +
> +       return ret;
> +}
> +
> +/**
> + * zynqmp_pm_clock_setrate - Set the clock rate for given id
> + * @clock_id:  ID of the clock
> + * @rate:      rate value in hz
> + *
> + * This function is used by master to set rate for any clock.
> + *
> + * Return:     Returns status, either success or error+reason.
> + */
So this can set rate only 4G max ?

> +static int zynqmp_pm_clock_setrate(u32 clock_id, u32 rate)
> +{
> +       return invoke_pm_fn(PM_CLOCK_SETRATE, clock_id, rate, 0, 0, NULL);
> +}
> +
> +/**
> + * zynqmp_pm_clock_getrate - Get the clock rate for given id
> + * @clock_id:  ID of the clock
> + * @rate:      rate value in hz
> + *
> + * This function is used by master to get rate
> + * for any clock.
> + *
> + * Return:     Returns status, either success or error+reason.
> + */
Same question here?

> +static int zynqmp_pm_clock_getrate(u32 clock_id, u32 *rate)
> +{
> +       u32 ret_payload[PAYLOAD_ARG_CNT];
> +       int ret;
> +
> +       ret = invoke_pm_fn(PM_CLOCK_GETRATE, clock_id, 0, 0, 0, ret_payload);
> +       *rate = ret_payload[1];
> +
> +       return ret;
> +}
> +
Also  what is the difference between set rate and set divider?