linux-kernel - Re: [PATCH 4/7] clk: zynqmp: Add support for get max divider

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Date:   Thu, 21 Nov 2019 15:33:16 +0100
From:   Michael Tretter <m.tretter@...gutronix.de>
To:     Rajan Vaja <rajan.vaja@...inx.com>
Cc:     mturquette@...libre.com, sboyd@...nel.org, robh+dt@...nel.org,
        mark.rutland@....com, michal.simek@...inx.com,
        jolly.shah@...inx.com, dan.carpenter@...cle.com,
        gustavo@...eddedor.com, tejas.patel@...inx.com,
        nava.manne@...inx.com, ravi.patel@...inx.com,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        m.tretter@...gutronix.de, kernel@...gutronix.de
Subject: Re: [PATCH 4/7] clk: zynqmp: Add support for get max divider

On Tue, 12 Nov 2019 05:16:17 -0800, Rajan Vaja wrote:
> To achieve best possible rate, maximum limit of divider is required
> while computation. Get maximum supported divisor from firmware. To
> maintain backward compatibility assign maximum possible value(0xFFFF)
> if query for max divisor is not successful.
> 
> Signed-off-by: Rajan Vaja <rajan.vaja@...inx.com>
> ---
>  drivers/clk/zynqmp/divider.c         | 19 +++++++++++++++++++
>  include/linux/firmware/xlnx-zynqmp.h |  1 +
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/clk/zynqmp/divider.c b/drivers/clk/zynqmp/divider.c
> index d8f5b70d..b79cd45 100644
> --- a/drivers/clk/zynqmp/divider.c
> +++ b/drivers/clk/zynqmp/divider.c
> @@ -41,6 +41,7 @@ struct zynqmp_clk_divider {
>  	bool is_frac;
>  	u32 clk_id;
>  	u32 div_type;
> +	u16 max_div;
>  };
>  
>  static inline int zynqmp_divider_get_val(unsigned long parent_rate,
> @@ -195,6 +196,9 @@ struct clk_hw *zynqmp_clk_register_divider(const char *name,
>  	struct clk_hw *hw;
>  	struct clk_init_data init;
>  	int ret;
> +	const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
> +	struct zynqmp_pm_query_data qdata = {0};
> +	u32 ret_payload[PAYLOAD_ARG_CNT];
>  
>  	/* allocate the divider */
>  	div = kzalloc(sizeof(*div), GFP_KERNEL);
> @@ -215,6 +219,21 @@ struct clk_hw *zynqmp_clk_register_divider(const char *name,
>  	div->clk_id = clk_id;
>  	div->div_type = nodes->type;
>  
> +	/*
> +	 * To achieve best possible rate, maximum limit of divider is required
> +	 * while computation. Get maximum supported divisor from firmware. To
> +	 * maintain backward compatibility assign maximum possible value(0xFFFF)
> +	 * if query for max divisor is not successful.
> +	 */
> +	qdata.qid = PM_QID_CLOCK_GET_MAX_DIVISOR;
> +	qdata.arg1 = clk_id;
> +	qdata.arg2 = nodes->type;
> +	ret = eemi_ops->query_data(qdata, ret_payload);
> +	if (ret)
> +		div->max_div = U16_MAX;
> +	else
> +		div->max_div = ret_payload[1];

Add a helper function for retrieving the max divisor. The clk_register
function should really not be mixed with code to access the firmware.

Michael

> +
>  	hw = &div->hw;
>  	ret = clk_hw_register(NULL, hw);
>  	if (ret) {
> diff --git a/include/linux/firmware/xlnx-zynqmp.h b/include/linux/firmware/xlnx-zynqmp.h
> index f019d1c..f0d4558 100644
> --- a/include/linux/firmware/xlnx-zynqmp.h
> +++ b/include/linux/firmware/xlnx-zynqmp.h
> @@ -114,6 +114,7 @@ enum pm_query_id {
>  	PM_QID_CLOCK_GET_PARENTS,
>  	PM_QID_CLOCK_GET_ATTRIBUTES,
>  	PM_QID_CLOCK_GET_NUM_CLOCKS = 12,
> +	PM_QID_CLOCK_GET_MAX_DIVISOR,
>  };
>  
>  enum zynqmp_pm_reset_action {