linux-kernel - Re: [PATCH V6] clk: qcom: Add spmi

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Date:   Fri, 17 Nov 2017 15:56:11 -0800
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Tirupathi Reddy <tirupath@...eaurora.org>
Cc:     mturquette@...libre.com, robh+dt@...nel.org, mark.rutland@....com,
        andy.gross@...aro.org, david.brown@...aro.org,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org
Subject: Re: [PATCH V6] clk: qcom: Add spmi_pmic clock divider support

On 11/17, Tirupathi Reddy wrote:
> diff --git a/Documentation/devicetree/bindings/clock/clk-spmi-pmic-div.txt b/Documentation/devicetree/bindings/clock/clk-spmi-pmic-div.txt
> new file mode 100644
> index 0000000..2cf2aba
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/clk-spmi-pmic-div.txt

Please move this to qcom,spmi-clkdiv.txt like other qcom bindings.

> @@ -0,0 +1,59 @@
> +Qualcomm Technologies, Inc. SPMI PMIC clock divider (clkdiv)
> +
> +clkdiv configures the clock frequency of a set of outputs on the PMIC.
> +These clocks are typically wired through alternate functions on
> +gpio pins.
> +
> +=======================
> +Properties
> +=======================
> +
> +- compatible
> +	Usage:      required
> +	Value type: <string>
> +	Definition: must be "qcom,spmi-clkdiv".
> +
> +- reg
> +	Usage:      required
> +	Value type: <prop-encoded-array>
> +	Definition: base address of CLKDIV peripherals.
> +
> +- qcom,num-clkdivs
> +	Usage:      required
> +	Value type: <u32>
> +	Definition: number of CLKDIV peripherals.

Would it work if we read the registers and looked for the clkdiv
subtype ID? If we read something that doesn't match, break and
stop adding clks? Or does reading the next "peripheral" cause
some sort of crash and burn scenario where the device see an
access control violation? Would be interesting to do it that way
and avoid needing a new property in DT.

> +
> +
> +	parent_name = of_clk_get_parent_name(of_node, 0);
> +	if (!parent_name) {
> +		dev_err(dev, "missing parent clock\n");
> +		return -ENODEV;
> +	}
> +
> +	init.parent_names = &parent_name;
> +	init.num_parents = 1;
> +	init.ops = &clk_spmi_pmic_div_ops;
> +
> +	for (i = 0, clkdiv = cc->clks; i < nclks; i++) {
> +		spin_lock_init(&clkdiv[i].lock);
> +		clkdiv[i].base = start + i * 0x100;
> +		clkdiv[i].regmap = regmap;
> +		clkdiv[i].cxo_period_ns = NSEC_PER_SEC / cxo_hz;
> +		init.name = kasprintf(GFP_KERNEL, "div_clk%d", i + 1);

Hmm. Maybe we should just have this on the stack. 20 characters
should be plenty?

> +		clkdiv[i].hw.init = &init;
> +
> +		ret = devm_clk_hw_register(dev, &clkdiv[i].hw);
> +		kfree(init.name); /* clk framework made a copy */
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return of_clk_add_hw_provider(of_node, spmi_pmic_div_clk_hw_get, cc);
> +}
> +
> +static int spmi_pmic_clkdiv_remove(struct platform_device *pdev)
> +{
> +	of_clk_del_provider(pdev->dev.of_node);
> +
> +	return 0;

This can use devm now.

> +}
> +
> +static const struct of_device_id spmi_pmic_clkdiv_match_table[] = {
> +	{ .compatible = "qcom,spmi-clkdiv" },
> +	{ /* sentinel */ }
> +};

Nice!

-- 
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