linux-kernel - Re: [PATCH 1/5] firmware: xilinx: Adds new eemi call for reg access

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Date:   Wed, 18 Dec 2019 14:55:26 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Jolly Shah <jolly.shah@...inx.com>
Cc:     ard.biesheuvel@...aro.org, mingo@...nel.org,
        gregkh@...uxfoundation.org, matt@...eblueprint.co.uk,
        hkallweit1@...il.com, keescook@...omium.org,
        dmitry.torokhov@...il.com, michal.simek@...inx.com,
        rajanv@...inx.com, Sudeep Holla <sudeep.holla@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Rajan Vaja <rajan.vaja@...inx.com>
Subject: Re: [PATCH 1/5] firmware: xilinx: Adds new eemi call for reg access

On Wed, Dec 04, 2019 at 03:29:15PM -0800, Jolly Shah wrote:
> From: Rajan Vaja <rajan.vaja@...inx.com>
> 
> This patch adds new EEMI call which is used for CSU/PMU register
> access from linux.
> 
> Signed-off-by: Michal Simek <michal.simek@...inx.com>
> Signed-off-by: Rajan Vaja <rajan.vaja@...inx.com>
> Signed-off-by: Jolly Shah <jolly.shah@...inx.com>
> ---
>  drivers/firmware/xilinx/zynqmp.c     | 183 +++++++++++++++++++++++++++++++++++
>  include/linux/firmware/xlnx-zynqmp.h |   9 ++
>  2 files changed, 192 insertions(+)
> 
> diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
> index fd3d837..56431ad 100644
> --- a/drivers/firmware/xilinx/zynqmp.c
> +++ b/drivers/firmware/xilinx/zynqmp.c
> @@ -24,6 +24,8 @@
>  #include <linux/firmware/xlnx-zynqmp.h>
>  #include "zynqmp-debug.h"
>  
> +static unsigned long register_address;
> +
>  static const struct zynqmp_eemi_ops *eemi_ops_tbl;
>  
>  static const struct mfd_cell firmware_devs[] = {
> @@ -664,6 +666,26 @@ static int zynqmp_pm_set_requirement(const u32 node, const u32 capabilities,
>  				   qos, ack, NULL);
>  }
>  
> +/**
> + * zynqmp_pm_config_reg_access - PM Config API for Config register access
> + * @register_access_id:	ID of the requested REGISTER_ACCESS
> + * @address:		Address of the register to be accessed
> + * @mask:		Mask to be written to the register
> + * @value:		Value to be written to the register
> + * @out:		Returned output value
> + *
> + * This function calls REGISTER_ACCESS to configure CSU/PMU registers.
> + *
> + * Return:	Returns status, either success or error+reason
> + */
> +
> +static int zynqmp_pm_config_reg_access(u32 register_access_id, u32 address,
> +				       u32 mask, u32 value, u32 *out)
> +{
> +	return zynqmp_pm_invoke_fn(PM_REGISTER_ACCESS, register_access_id,
> +				   address, mask, value, out);
> +}
> +

If you have this API, can you remove all other APIs and implement them
using these ? This kills the EEMI abstraction.

NACK for this and any attempts to provide direct reas/write access to
the PM config space. EEMI should have better abstraction than this.

--
Regards,
Sudeep