linux-kernel - Re: [PATCH v4 1/7] x86: clk: clk-fch: Add support for newer family of AMD's SOC

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Date:   Tue, 30 Nov 2021 13:41:30 -0600
From:   "Limonciello, Mario" <mario.limonciello@....com>
To:     Ajit Kumar Pandey <AjitKumar.Pandey@....com>, sboyd@...nel.org,
        rafael@...nel.org, linux-clk@...r.kernel.org
Cc:     Vijendar.Mukunda@....com, Alexander.Deucher@....com,
        Basavaraj.Hiregoudar@....com, Sunil-kumar.Dommati@....com,
        Michael Turquette <mturquette@...libre.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/7] x86: clk: clk-fch: Add support for newer family of
 AMD's SOC

On 11/25/2021 05:04, Ajit Kumar Pandey wrote:
> FCH controller clock configuration slightly differs across AMD's
> SOC architectures. Newer family of SOC only support a 48MHz fixed
> clock while older family has a clk_mux to choose 48MHz and 25MHz.
> At present fixed clk support is only enabled for RV architecture
> using "is-rv" device property initialized from boot loader. This
> limit 48MHz fixed clock gate support to RV platform unless we add
> similar device property in boot loader for other architecture.
> 
> Add pci_device_id table with Raven platform id and replace "is-rv"
> device property check with pci id match to support 48MHz fixed clk
> support. This enhanced flexibility to enable fixed 48MHz fch clock
> framework on other architectures by simply adding new entries into
> pci_device_id table. Also replace RV with FIXED as generic naming
> convention across all platforms.
> 
> Signed-off-by: Ajit Kumar Pandey <AjitKumar.Pandey@....com>
> ---
>   drivers/clk/x86/clk-fch.c | 41 ++++++++++++++++++++++++++++++---------
>   1 file changed, 32 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/clk/x86/clk-fch.c b/drivers/clk/x86/clk-fch.c
> index 8f7c5142b0f0..de556b03e184 100644
> --- a/drivers/clk/x86/clk-fch.c
> +++ b/drivers/clk/x86/clk-fch.c
> @@ -1,6 +1,6 @@
>   // SPDX-License-Identifier: MIT
>   /*
> - * clock framework for AMD Stoney based clocks
> + * clock framework for AMD FCH controller block
>    *
>    * Copyright 2018 Advanced Micro Devices, Inc.
>    */
> @@ -8,6 +8,7 @@
>   #include <linux/clk.h>
>   #include <linux/clkdev.h>
>   #include <linux/clk-provider.h>
> +#include <linux/pci.h>
>   #include <linux/platform_data/clk-fch.h>
>   #include <linux/platform_device.h>
>   
> @@ -26,22 +27,37 @@
>   #define ST_CLK_GATE	3
>   #define ST_MAX_CLKS	4
>   
> -#define RV_CLK_48M	0
> -#define RV_CLK_GATE	1
> -#define RV_MAX_CLKS	2
> +#define CLK_48M_FIXED	0
> +#define CLK_GATE_FIXED	1
> +#define CLK_MAX_FIXED	2
> +
> +/* List of supported CPU ids for fixed clk */
> +#define AMD_CPU_ID_RV			0x15D0
>   
>   static const char * const clk_oscout1_parents[] = { "clk48MHz", "clk25MHz" };
>   static struct clk_hw *hws[ST_MAX_CLKS];
>   
> +static const struct pci_device_id soc_pci_ids[] = {
> +	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, AMD_CPU_ID_RV) },
> +	{ }
> +};
> +

Have you considered inverting it?  The number of ASICs using the "older" 
design with the mux and multiple clock sources is a fixed value, but 
we'll keep adding new ASICs in the "new" design of just 48Mhz.

Notably; I see that this series is missing the Yellow Carp ID for 
example.  We'll keep having more designs with the 48Mhz that need to be 
added to this list.


>   static int fch_clk_probe(struct platform_device *pdev)
>   {
>   	struct fch_clk_data *fch_data;
> +	struct pci_dev *rdev;
>   
>   	fch_data = dev_get_platdata(&pdev->dev);
>   	if (!fch_data || !fch_data->base)
>   		return -EINVAL;
>   
> -	if (!fch_data->is_rv) {
> +	rdev = pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(0, 0));
> +	if (!rdev) {
> +		dev_err(&pdev->dev, "FCH device not found\n");
> +		return -ENODEV;
> +	}
> +
> +	if (!pci_match_id(soc_pci_ids, rdev)) {
>   		hws[ST_CLK_48M] = clk_hw_register_fixed_rate(NULL, "clk48MHz",
>   			NULL, 0, 48000000);
>   		hws[ST_CLK_25M] = clk_hw_register_fixed_rate(NULL, "clk25MHz",
> @@ -61,17 +77,18 @@ static int fch_clk_probe(struct platform_device *pdev)
>   		devm_clk_hw_register_clkdev(&pdev->dev, hws[ST_CLK_GATE],
>   			"oscout1", NULL);
>   	} else {
> -		hws[RV_CLK_48M] = clk_hw_register_fixed_rate(NULL, "clk48MHz",
> +		hws[CLK_48M_FIXED] = clk_hw_register_fixed_rate(NULL, "clk48MHz",
>   			NULL, 0, 48000000);
>   
> -		hws[RV_CLK_GATE] = clk_hw_register_gate(NULL, "oscout1",
> +		hws[CLK_GATE_FIXED] = clk_hw_register_gate(NULL, "oscout1",
>   			"clk48MHz", 0, fch_data->base + MISCCLKCNTL1,
>   			OSCCLKENB, CLK_GATE_SET_TO_DISABLE, NULL);
>   
> -		devm_clk_hw_register_clkdev(&pdev->dev, hws[RV_CLK_GATE],
> +		devm_clk_hw_register_clkdev(&pdev->dev, hws[CLK_GATE_FIXED],
>   			"oscout1", NULL);
>   	}
>   
> +	pci_dev_put(rdev);
>   	return 0;
>   }
>   
> @@ -79,14 +96,20 @@ static int fch_clk_remove(struct platform_device *pdev)
>   {
>   	int i, clks;
>   	struct fch_clk_data *fch_data;
> +	struct pci_dev *rdev;
>   
>   	fch_data = dev_get_platdata(&pdev->dev);
>   
> -	clks = fch_data->is_rv ? RV_MAX_CLKS : ST_MAX_CLKS;
> +	rdev = pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(0, 0));
> +	if (!rdev)
> +		return -ENODEV;
> +
> +	clks = pci_match_id(soc_pci_ids, rdev) ? CLK_MAX_FIXED : ST_MAX_CLKS;
>   
>   	for (i = 0; i < clks; i++)
>   		clk_hw_unregister(hws[i]);
>   
> +	pci_dev_put(rdev);
>   	return 0;
>   }
>   
>