Re: [PATCH 7/8] cpufreq: sc520_freq: Drop support for AMD Elan SC520

[Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>]

On 5/6/2026 10:42 PM, Sean Young wrote:
> Since commit 8b793a92d862 ("x86/cpu: Remove M486/M486SX/ELAN support"),
> the AMD Elan SC520 is no longer supported, so the cpu frequency
> driver is no longer needed.
> 
> Signed-off-by: Sean Young <sean@mess.org>


Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>

> ---
>   drivers/cpufreq/Kconfig.x86  |  11 ---
>   drivers/cpufreq/Makefile     |   1 -
>   drivers/cpufreq/sc520_freq.c | 136 -----------------------------------
>   3 files changed, 148 deletions(-)
>   delete mode 100644 drivers/cpufreq/sc520_freq.c
> 
> diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86
> index 027e6ea2e038..865b290b01ff 100644
> --- a/drivers/cpufreq/Kconfig.x86
> +++ b/drivers/cpufreq/Kconfig.x86
> @@ -141,17 +141,6 @@ config ELAN_CPUFREQ
>   
>   	  If in doubt, say N.
>   
> -config SC520_CPUFREQ
> -	tristate "AMD Elan SC520"
> -	depends on MELAN
> -	help
> -	  This adds the CPUFreq driver for AMD Elan SC520 processor.
> -
> -	  For details, take a look at <file:Documentation/cpu-freq/>.
> -
> -	  If in doubt, say N.
> -
> -
>   config X86_POWERNOW_K6
>   	tristate "AMD Mobile K6-2/K6-3 PowerNow!"
>   	depends on X86_32
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index 385c9fcc65c6..96196edf79d5 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -41,7 +41,6 @@ obj-$(CONFIG_X86_POWERNOW_K7)		+= powernow-k7.o
>   obj-$(CONFIG_X86_LONGHAUL)		+= longhaul.o
>   obj-$(CONFIG_X86_E_POWERSAVER)		+= e_powersaver.o
>   obj-$(CONFIG_ELAN_CPUFREQ)		+= elanfreq.o
> -obj-$(CONFIG_SC520_CPUFREQ)		+= sc520_freq.o
>   obj-$(CONFIG_X86_LONGRUN)		+= longrun.o
>   obj-$(CONFIG_X86_GX_SUSPMOD)		+= gx-suspmod.o
>   obj-$(CONFIG_X86_SPEEDSTEP_ICH)		+= speedstep-ich.o
> diff --git a/drivers/cpufreq/sc520_freq.c b/drivers/cpufreq/sc520_freq.c
> deleted file mode 100644
> index b360f03a116f..000000000000
> --- a/drivers/cpufreq/sc520_freq.c
> +++ /dev/null
> @@ -1,136 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0-or-later
> -/*
> - *	sc520_freq.c: cpufreq driver for the AMD Elan sc520
> - *
> - *	Copyright (C) 2005 Sean Young <sean@mess.org>
> - *
> - *	Based on elanfreq.c
> - *
> - *	2005-03-30: - initial revision
> - */
> -
> -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> -
> -#include <linux/kernel.h>
> -#include <linux/module.h>
> -#include <linux/init.h>
> -
> -#include <linux/delay.h>
> -#include <linux/cpufreq.h>
> -#include <linux/timex.h>
> -#include <linux/io.h>
> -
> -#include <asm/cpu_device_id.h>
> -
> -#define MMCR_BASE	0xfffef000	/* The default base address */
> -#define OFFS_CPUCTL	0x2   /* CPU Control Register */
> -
> -static __u8 __iomem *cpuctl;
> -
> -static struct cpufreq_frequency_table sc520_freq_table[] = {
> -	{0, 0x01,	100000},
> -	{0, 0x02,	133000},
> -	{0, 0,	CPUFREQ_TABLE_END},
> -};
> -
> -static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu)
> -{
> -	u8 clockspeed_reg = *cpuctl;
> -
> -	switch (clockspeed_reg & 0x03) {
> -	default:
> -		pr_err("error: cpuctl register has unexpected value %02x\n",
> -		       clockspeed_reg);
> -		fallthrough;
> -	case 0x01:
> -		return 100000;
> -	case 0x02:
> -		return 133000;
> -	}
> -}
> -
> -static int sc520_freq_target(struct cpufreq_policy *policy, unsigned int state)
> -{
> -
> -	u8 clockspeed_reg;
> -
> -	local_irq_disable();
> -
> -	clockspeed_reg = *cpuctl & ~0x03;
> -	*cpuctl = clockspeed_reg | sc520_freq_table[state].driver_data;
> -
> -	local_irq_enable();
> -
> -	return 0;
> -}
> -
> -/*
> - *	Module init and exit code
> - */
> -
> -static int sc520_freq_cpu_init(struct cpufreq_policy *policy)
> -{
> -	struct cpuinfo_x86 *c = &cpu_data(0);
> -
> -	/* capability check */
> -	if (c->x86_vendor != X86_VENDOR_AMD ||
> -	    c->x86 != 4 || c->x86_model != 9)
> -		return -ENODEV;
> -
> -	/* cpuinfo and default policy values */
> -	policy->cpuinfo.transition_latency = 1000000; /* 1ms */
> -	policy->freq_table = sc520_freq_table;
> -
> -	return 0;
> -}
> -
> -
> -static struct cpufreq_driver sc520_freq_driver = {
> -	.get	= sc520_freq_get_cpu_frequency,
> -	.verify	= cpufreq_generic_frequency_table_verify,
> -	.target_index = sc520_freq_target,
> -	.init	= sc520_freq_cpu_init,
> -	.name	= "sc520_freq",
> -};
> -
> -static const struct x86_cpu_id sc520_ids[] = {
> -	X86_MATCH_VENDOR_FAM_MODEL(AMD, 4, 9, NULL),
> -	{}
> -};
> -MODULE_DEVICE_TABLE(x86cpu, sc520_ids);
> -
> -static int __init sc520_freq_init(void)
> -{
> -	int err;
> -
> -	if (!x86_match_cpu(sc520_ids))
> -		return -ENODEV;
> -
> -	cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1);
> -	if (!cpuctl) {
> -		pr_err("sc520_freq: error: failed to remap memory\n");
> -		return -ENOMEM;
> -	}
> -
> -	err = cpufreq_register_driver(&sc520_freq_driver);
> -	if (err)
> -		iounmap(cpuctl);
> -
> -	return err;
> -}
> -
> -
> -static void __exit sc520_freq_exit(void)
> -{
> -	cpufreq_unregister_driver(&sc520_freq_driver);
> -	iounmap(cpuctl);
> -}
> -
> -
> -MODULE_LICENSE("GPL");
> -MODULE_AUTHOR("Sean Young <sean@mess.org>");
> -MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU");
> -
> -module_init(sc520_freq_init);
> -module_exit(sc520_freq_exit);
> -


-- 
Thx and BRs,
Zhongqiu Han