linux-kernel - Re: [PATCH 2/2] clk: qcom: Add ipq6018 apss clock controller

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Date:   Mon, 09 Mar 2020 13:24:35 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Sivaprakash Murugesan <sivaprak@...eaurora.org>, agross@...nel.org,
        bjorn.andersson@...aro.org, devicetree@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, mturquette@...libre.com,
        robh+dt@...nel.org
Cc:     sivaprak@...eaurora.org
Subject: Re: [PATCH 2/2] clk: qcom: Add ipq6018 apss clock controller

Quoting Sivaprakash Murugesan (2020-02-27 01:55:18)
> diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
> index 15cdcdc..37e4ce2 100644
> --- a/drivers/clk/qcom/Kconfig
> +++ b/drivers/clk/qcom/Kconfig
> @@ -89,6 +89,14 @@ config APQ_MMCC_8084
>           Say Y if you want to support multimedia devices such as display,
>           graphics, video encode/decode, camera, etc.
>  
> +config IPQ_APSS_6018
> +       tristate "IPQ6018 APSS Clock Controller"
> +       select IPQ_GCC_6018
> +       help
> +         Support for APSS clock controller on ipq6018 devices. The
> +         APSS clock controller supports frequencies higher than 800Mhz.

supports CPU frequencies? It's not clear what APSS is to a lot of people
out there.

> +         Say Y if you want to support higher frequencies on ipq6018 devices.

support CPU frequency scaling on ipq6018?

> +
>  config IPQ_GCC_4019
>         tristate "IPQ4019 Global Clock Controller"
>         help
> diff --git a/drivers/clk/qcom/apss-ipq6018.c b/drivers/clk/qcom/apss-ipq6018.c
> new file mode 100644
> index 0000000..04b8962
> --- /dev/null
> +++ b/drivers/clk/qcom/apss-ipq6018.c
> @@ -0,0 +1,210 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/err.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>

> +#include <linux/of.h>
> +#include <linux/of_device.h>

Are these two includes needed at all?

> +#include <linux/clk-provider.h>
> +#include <linux/regmap.h>
> +
> +#include <linux/reset-controller.h>
> +#include <dt-bindings/clock/qcom,apss-ipq6018.h>
> +
> +#include "common.h"
> +#include "clk-regmap.h"
> +#include "clk-pll.h"
> +#include "clk-rcg.h"
> +#include "clk-branch.h"
> +#include "clk-alpha-pll.h"
> +#include "clk-regmap-divider.h"
> +#include "clk-regmap-mux.h"
> +#include "reset.h"
> +
> +#define F(f, s, h, m, n) { (f), (s), (2 * (h) - 1), (m), (n) }

This can be removed. It's common in clk-rcg.h now

> +
> +static struct clk_branch apcs_alias0_core_clk = {
> +       .halt_reg = 0x004c,
> +       .clkr = {
> +               .enable_reg = 0x004c,
> +               .enable_mask = BIT(0),
> +               .hw.init = &(struct clk_init_data){
> +                       .name = "apcs_alias0_core_clk",
> +                       .parent_hws = (const struct clk_hw *[]){
> +                               &apcs_alias0_clk_src.clkr.hw },
> +                       .num_parents = 1,
> +                       .flags = CLK_SET_RATE_PARENT | CLK_IS_CRITICAL,

Please add a comment about why CLK_IS_CRITICAL is here. Presumably in
the case that a cpufreq driver doesn't probe and claim this clk?

> +                       .ops = &clk_branch2_ops,
> +               },
> +       },
> +};
> +
> +
[...]
> +
> +static int __init apss_ipq6018_init(void)
> +{
> +       return platform_driver_register(&apss_ipq6018_driver);
> +}
> +core_initcall(apss_ipq6018_init);
> +
> +static void __exit apss_ipq6018_exit(void)
> +{
> +       platform_driver_unregister(&apss_ipq6018_driver);
> +}
> +module_exit(apss_ipq6018_exit);

Any reason this can't just be module_platform_driver()?