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Message-ID: <20221025050744.43ttt5u2hx3q7dy5@vireshk-i7>
Date: Tue, 25 Oct 2022 10:37:44 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Arnd Bergmann <arnd@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org,
Russell King <linux@...linux.org.uk>,
Linus Walleij <linus.walleij@...aro.org>,
Lubomir Rintel <lkundrak@...sk>,
"Rafael J. Wysocki" <rafael@...nel.org>,
linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
Randy Dunlap <rdunlap@...radead.org>, linux-pm@...r.kernel.org
Subject: Re: [PATCH 05/11] cpufreq: remove sa1100 driver
On 21-10-22, 17:49, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
>
> The sa11xx platform has two cpufreq drivers, one for the older
> StrongARM1100 SoC, and a second one for StrongARM1110. After
> the removal of most SA1100 based machines, this driver is unused,
> and only the sa1110-cpufreq driver remains.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
> drivers/cpufreq/Kconfig | 2 +-
> drivers/cpufreq/Kconfig.arm | 3 -
> drivers/cpufreq/Makefile | 1 -
> drivers/cpufreq/sa1100-cpufreq.c | 206 -------------------------------
> 4 files changed, 1 insertion(+), 211 deletions(-)
> delete mode 100644 drivers/cpufreq/sa1100-cpufreq.c
>
> diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
> index 2a84fc63371e..8466f78651fc 100644
> --- a/drivers/cpufreq/Kconfig
> +++ b/drivers/cpufreq/Kconfig
> @@ -37,7 +37,7 @@ config CPU_FREQ_STAT
>
> choice
> prompt "Default CPUFreq governor"
> - default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
> + default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1110_CPUFREQ
> default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if ARM64 || ARM
> default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if X86_INTEL_PSTATE && SMP
> default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 82e5de1f6f8c..8f7a1065f344 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -277,9 +277,6 @@ config ARM_S5PV210_CPUFREQ
>
> If in doubt, say N.
>
> -config ARM_SA1100_CPUFREQ
> - bool
> -
> config ARM_SA1110_CPUFREQ
> bool
>
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index 49b98c62c5af..8de99b213146 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -78,7 +78,6 @@ obj-$(CONFIG_ARM_S3C64XX_CPUFREQ) += s3c64xx-cpufreq.o
> obj-$(CONFIG_ARM_S3C24XX_CPUFREQ) += s3c24xx-cpufreq.o
> obj-$(CONFIG_ARM_S3C24XX_CPUFREQ_DEBUGFS) += s3c24xx-cpufreq-debugfs.o
> obj-$(CONFIG_ARM_S5PV210_CPUFREQ) += s5pv210-cpufreq.o
> -obj-$(CONFIG_ARM_SA1100_CPUFREQ) += sa1100-cpufreq.o
> obj-$(CONFIG_ARM_SA1110_CPUFREQ) += sa1110-cpufreq.o
> obj-$(CONFIG_ARM_SCMI_CPUFREQ) += scmi-cpufreq.o
> obj-$(CONFIG_ARM_SCPI_CPUFREQ) += scpi-cpufreq.o
> diff --git a/drivers/cpufreq/sa1100-cpufreq.c b/drivers/cpufreq/sa1100-cpufreq.c
> deleted file mode 100644
> index 252b9fc26124..000000000000
> --- a/drivers/cpufreq/sa1100-cpufreq.c
> +++ /dev/null
> @@ -1,206 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0-or-later
> -/*
> - * cpu-sa1100.c: clock scaling for the SA1100
> - *
> - * Copyright (C) 2000 2001, The Delft University of Technology
> - *
> - * Authors:
> - * - Johan Pouwelse (J.A.Pouwelse@....tudelft.nl): initial version
> - * - Erik Mouw (J.A.K.Mouw@....tudelft.nl):
> - * - major rewrite for linux-2.3.99
> - * - rewritten for the more generic power management scheme in
> - * linux-2.4.5-rmk1
> - *
> - * This software has been developed while working on the LART
> - * computing board (http://www.lartmaker.nl/), which is
> - * sponsored by the Mobile Multi-media Communications
> - * (http://www.mobimedia.org/) and Ubiquitous Communications
> - * (http://www.ubicom.tudelft.nl/) projects.
> - *
> - * The authors can be reached at:
> - *
> - * Erik Mouw
> - * Information and Communication Theory Group
> - * Faculty of Information Technology and Systems
> - * Delft University of Technology
> - * P.O. Box 5031
> - * 2600 GA Delft
> - * The Netherlands
> - *
> - * Theory of operations
> - * ====================
> - *
> - * Clock scaling can be used to lower the power consumption of the CPU
> - * core. This will give you a somewhat longer running time.
> - *
> - * The SA-1100 has a single register to change the core clock speed:
> - *
> - * PPCR 0x90020014 PLL config
> - *
> - * However, the DRAM timings are closely related to the core clock
> - * speed, so we need to change these, too. The used registers are:
> - *
> - * MDCNFG 0xA0000000 DRAM config
> - * MDCAS0 0xA0000004 Access waveform
> - * MDCAS1 0xA0000008 Access waveform
> - * MDCAS2 0xA000000C Access waveform
> - *
> - * Care must be taken to change the DRAM parameters the correct way,
> - * because otherwise the DRAM becomes unusable and the kernel will
> - * crash.
> - *
> - * The simple solution to avoid a kernel crash is to put the actual
> - * clock change in ROM and jump to that code from the kernel. The main
> - * disadvantage is that the ROM has to be modified, which is not
> - * possible on all SA-1100 platforms. Another disadvantage is that
> - * jumping to ROM makes clock switching unnecessary complicated.
> - *
> - * The idea behind this driver is that the memory configuration can be
> - * changed while running from DRAM (even with interrupts turned on!)
> - * as long as all re-configuration steps yield a valid DRAM
> - * configuration. The advantages are clear: it will run on all SA-1100
> - * platforms, and the code is very simple.
> - *
> - * If you really want to understand what is going on in
> - * sa1100_update_dram_timings(), you'll have to read sections 8.2,
> - * 9.5.7.3, and 10.2 from the "Intel StrongARM SA-1100 Microprocessor
> - * Developers Manual" (available for free from Intel).
> - */
> -
> -#include <linux/kernel.h>
> -#include <linux/types.h>
> -#include <linux/init.h>
> -#include <linux/cpufreq.h>
> -#include <linux/io.h>
> -
> -#include <asm/cputype.h>
> -
> -#include <mach/generic.h>
> -#include <mach/hardware.h>
> -
> -struct sa1100_dram_regs {
> - int speed;
> - u32 mdcnfg;
> - u32 mdcas0;
> - u32 mdcas1;
> - u32 mdcas2;
> -};
> -
> -
> -static struct cpufreq_driver sa1100_driver;
> -
> -static struct sa1100_dram_regs sa1100_dram_settings[] = {
> - /*speed, mdcnfg, mdcas0, mdcas1, mdcas2, clock freq */
> - { 59000, 0x00dc88a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 59.0 MHz */
> - { 73700, 0x011490a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 73.7 MHz */
> - { 88500, 0x014e90a3, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 88.5 MHz */
> - {103200, 0x01889923, 0xcccccccf, 0xfffffffc, 0xffffffff},/* 103.2 MHz */
> - {118000, 0x01c29923, 0x9999998f, 0xfffffff9, 0xffffffff},/* 118.0 MHz */
> - {132700, 0x01fb2123, 0x9999998f, 0xfffffff9, 0xffffffff},/* 132.7 MHz */
> - {147500, 0x02352123, 0x3333330f, 0xfffffff3, 0xffffffff},/* 147.5 MHz */
> - {162200, 0x026b29a3, 0x38e38e1f, 0xfff8e38e, 0xffffffff},/* 162.2 MHz */
> - {176900, 0x02a329a3, 0x71c71c1f, 0xfff1c71c, 0xffffffff},/* 176.9 MHz */
> - {191700, 0x02dd31a3, 0xe38e383f, 0xffe38e38, 0xffffffff},/* 191.7 MHz */
> - {206400, 0x03153223, 0xc71c703f, 0xffc71c71, 0xffffffff},/* 206.4 MHz */
> - {221200, 0x034fba23, 0xc71c703f, 0xffc71c71, 0xffffffff},/* 221.2 MHz */
> - {235900, 0x03853a23, 0xe1e1e07f, 0xe1e1e1e1, 0xffffffe1},/* 235.9 MHz */
> - {250700, 0x03bf3aa3, 0xc3c3c07f, 0xc3c3c3c3, 0xffffffc3},/* 250.7 MHz */
> - {265400, 0x03f7c2a3, 0xc3c3c07f, 0xc3c3c3c3, 0xffffffc3},/* 265.4 MHz */
> - {280200, 0x0431c2a3, 0x878780ff, 0x87878787, 0xffffff87},/* 280.2 MHz */
> - { 0, 0, 0, 0, 0 } /* last entry */
> -};
> -
> -static void sa1100_update_dram_timings(int current_speed, int new_speed)
> -{
> - struct sa1100_dram_regs *settings = sa1100_dram_settings;
> -
> - /* find speed */
> - while (settings->speed != 0) {
> - if (new_speed == settings->speed)
> - break;
> -
> - settings++;
> - }
> -
> - if (settings->speed == 0) {
> - panic("%s: couldn't find dram setting for speed %d\n",
> - __func__, new_speed);
> - }
> -
> - /* No risk, no fun: run with interrupts on! */
> - if (new_speed > current_speed) {
> - /* We're going FASTER, so first relax the memory
> - * timings before changing the core frequency
> - */
> -
> - /* Half the memory access clock */
> - MDCNFG |= MDCNFG_CDB2;
> -
> - /* The order of these statements IS important, keep 8
> - * pulses!!
> - */
> - MDCAS2 = settings->mdcas2;
> - MDCAS1 = settings->mdcas1;
> - MDCAS0 = settings->mdcas0;
> - MDCNFG = settings->mdcnfg;
> - } else {
> - /* We're going SLOWER: first decrease the core
> - * frequency and then tighten the memory settings.
> - */
> -
> - /* Half the memory access clock */
> - MDCNFG |= MDCNFG_CDB2;
> -
> - /* The order of these statements IS important, keep 8
> - * pulses!!
> - */
> - MDCAS0 = settings->mdcas0;
> - MDCAS1 = settings->mdcas1;
> - MDCAS2 = settings->mdcas2;
> - MDCNFG = settings->mdcnfg;
> - }
> -}
> -
> -static int sa1100_target(struct cpufreq_policy *policy, unsigned int ppcr)
> -{
> - unsigned int cur = sa11x0_getspeed(0);
> - unsigned int new_freq;
> -
> - new_freq = sa11x0_freq_table[ppcr].frequency;
> -
> - if (new_freq > cur)
> - sa1100_update_dram_timings(cur, new_freq);
> -
> - PPCR = ppcr;
> -
> - if (new_freq < cur)
> - sa1100_update_dram_timings(cur, new_freq);
> -
> - return 0;
> -}
> -
> -static int __init sa1100_cpu_init(struct cpufreq_policy *policy)
> -{
> - cpufreq_generic_init(policy, sa11x0_freq_table, 0);
> - return 0;
> -}
> -
> -static struct cpufreq_driver sa1100_driver __refdata = {
> - .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK |
> - CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
> - .verify = cpufreq_generic_frequency_table_verify,
> - .target_index = sa1100_target,
> - .get = sa11x0_getspeed,
> - .init = sa1100_cpu_init,
> - .name = "sa1100",
> -};
> -
> -static int __init sa1100_dram_init(void)
> -{
> - if (cpu_is_sa1100())
> - return cpufreq_register_driver(&sa1100_driver);
> - else
> - return -ENODEV;
> -}
> -
> -arch_initcall(sa1100_dram_init);
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
--
viresh
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