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Message-ID: <20150420141719.GF27115@jcartwri.amer.corp.natinst.com>
Date: Mon, 20 Apr 2015 09:17:19 -0500
From: Josh Cartwright <joshc@...com>
To: "pi-cheng.chen" <pi-cheng.chen@...aro.org>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
Mike Turquette <mturquette@...aro.org>,
Matthias Brugger <matthias.bgg@...il.com>,
devicetree@...r.kernel.org, linaro-kernel@...ts.linaro.org,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
fan.chen@...iatek.com, Howard Chen <ibanezchen@...il.com>,
linux-mediatek@...ts.infradead.org,
"Joe.C" <yingjoe.chen@...iatek.com>,
Eddie Huang <eddie.huang@...iatek.com>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/2] cpufreq: mediatek: Add MT8173 cpufreq driver
On Mon, Apr 20, 2015 at 05:27:26PM +0800, pi-cheng.chen wrote:
> This patch implements MT8173 specific cpufreq driver with OPP table defined
> in the driver code.
>
> Signed-off-by: pi-cheng.chen <pi-cheng.chen@...aro.org>
> ---
> drivers/cpufreq/Kconfig.arm | 6 +
> drivers/cpufreq/Makefile | 1 +
> drivers/cpufreq/mt8173-cpufreq.c | 509 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 516 insertions(+)
> create mode 100644 drivers/cpufreq/mt8173-cpufreq.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 1b06fc4..25643c7 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -132,6 +132,12 @@ config ARM_KIRKWOOD_CPUFREQ
> This adds the CPUFreq driver for Marvell Kirkwood
> SoCs.
>
> +config ARM_MT8173_CPUFREQ
> + bool "Mediatek MT8173 CPUFreq support"
> + depends on ARCH_MEDIATEK && REGULATOR
I think you want to 'select REGULATOR' here; because REGULATOR isn't
a user-visible option.
> + help
> + This adds the CPUFreq driver support for Mediatek MT8173 SoC.
> +
> config ARM_OMAP2PLUS_CPUFREQ
> bool "TI OMAP2+"
> depends on ARCH_OMAP2PLUS
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index 82a1821..da9d616 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -62,6 +62,7 @@ obj-$(CONFIG_ARM_HIGHBANK_CPUFREQ) += highbank-cpufreq.o
> obj-$(CONFIG_ARM_IMX6Q_CPUFREQ) += imx6q-cpufreq.o
> obj-$(CONFIG_ARM_INTEGRATOR) += integrator-cpufreq.o
> obj-$(CONFIG_ARM_KIRKWOOD_CPUFREQ) += kirkwood-cpufreq.o
> +obj-$(CONFIG_ARM_MT8173_CPUFREQ) += mt8173-cpufreq.o
> obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ) += omap-cpufreq.o
> obj-$(CONFIG_ARM_PXA2xx_CPUFREQ) += pxa2xx-cpufreq.o
> obj-$(CONFIG_PXA3xx) += pxa3xx-cpufreq.o
> diff --git a/drivers/cpufreq/mt8173-cpufreq.c b/drivers/cpufreq/mt8173-cpufreq.c
> new file mode 100644
> index 0000000..a310e72
> --- /dev/null
> +++ b/drivers/cpufreq/mt8173-cpufreq.c
> @@ -0,0 +1,509 @@
> +/*
> +* Copyright (c) 2015 Linaro Ltd.
> +* Author: Pi-Cheng Chen <pi-cheng.chen@...aro.org>
> +*
> +* This program is free software; you can redistribute it and/or modify
> +* it under the terms of the GNU General Public License version 2 as
> +* published by the Free Software Foundation.
> +*
> +* This program is distributed in the hope that it will be useful,
> +* but WITHOUT ANY WARRANTY; without even the implied warranty of
> +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +* GNU General Public License for more details.
> +*/
> +
> +#include <linux/clk.h>
> +#include <linux/cpu.h>
> +#include <linux/cpufreq.h>
> +#include <linux/cpumask.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +#define MIN_VOLT_SHIFT 100000
> +#define MAX_VOLT_SHIFT 200000
> +
> +#define OPP(f, vp, vs) { \
> + .freq = f, \
> + .vproc = vp, \
> + .vsram = vs, \
> + }
> +
> +struct mtk_cpu_opp {
> + unsigned int freq;
> + int vproc;
> + int vsram;
> +};
> +
> +/*
> + * The struct cpu_dvfs_info holds necessary information for doing CPU DVFS of
> + * each cluster. For Mediatek SoCs, each CPU cluster in SoC has two voltage
> + * inputs, Vproc and Vsram. For some cluster in SoC, the two voltage inputs are
> + * supplied by different PMICs. In this case, when scaling up/down the voltage
> + * of Vsram and Vproc, the two voltage inputs need to be controlled under a
> + * hardware limitation: 100mV < Vsram - Vproc < 200mV
> + * When scaling up/down the clock frequency of a cluster, the clock source need
> + * to be switched to another stable PLL clock temporarily, and switched back to
> + * the original PLL after the it becomes stable at target frequency.
> + * Hence the voltage inputs of cluster need to be set to an intermediate voltage
> + * before the clock frequency being scaled up/down.
> + */
> +
> +struct cpu_dvfs_info {
> + cpumask_t cpus;
> +
> + struct mtk_cpu_opp *opp_tbl;
> + struct mtk_cpu_opp *intermediate_opp;
> + int nr_opp;
> +
> + struct regulator *proc_reg;
> + struct regulator *sram_reg;
> + struct clk *cpu_clk;
> + struct clk *inter_pll;
> +};
> +
> +/*
> + * This is a temporary solution until we have new OPPv2 bindings. Therefore we
> + * could describe the OPPs with (freq, volt, volt) tuple properly in device
> + * tree.
> + */
> +
> +/* OPP table for LITTLE cores of MT8173 */
> +struct mtk_cpu_opp mt8173_l_opp[] = {
static const?
> + OPP(507000000, 859000, 0),
> + OPP(702000000, 908000, 0),
> + OPP(1001000000, 983000, 0),
> + OPP(1105000000, 1009000, 0),
> + OPP(1183000000, 1028000, 0),
> + OPP(1404000000, 1083000, 0),
> + OPP(1508000000, 1109000, 0),
> + OPP(1573000000, 1125000, 0),
> +};
> +
> +/* OPP table for big cores of MT8173 */
> +struct mtk_cpu_opp mt8173_b_opp[] = {
same here?
> + OPP(507000000, 828000, 928000),
> + OPP(702000000, 867000, 967000),
> + OPP(1001000000, 927000, 1027000),
> + OPP(1209000000, 968000, 1068000),
> + OPP(1404000000, 1007000, 1107000),
> + OPP(1612000000, 1049000, 1149000),
> + OPP(1807000000, 1089000, 1150000),
> + OPP(1989000000, 1125000, 1150000),
> +};
> +
[..]
> +static int mtk_cpufreq_voltage_trace(struct cpu_dvfs_info *info,
> + struct mtk_cpu_opp *opp)
> +{
> + struct regulator *proc_reg = info->proc_reg;
> + struct regulator *sram_reg = info->sram_reg;
> + int old_vproc, new_vproc, old_vsram, new_vsram, vsram, vproc, ret;
> +
> + old_vproc = regulator_get_voltage(proc_reg);
> + old_vsram = regulator_get_voltage(sram_reg);
> +
> + new_vproc = opp->vproc;
> + new_vsram = opp->vsram;
> +
> + /*
> + * In the case the voltage is going to be scaled up, Vsram and Vproc
> + * need to be scaled up step by step. In each step, Vsram needs to be
> + * set to (Vproc + 200mV) first, then Vproc is set to (Vsram - 100mV).
> + * Repeat the step until Vsram and Vproc are set to target voltage.
> + */
> + if (old_vproc < new_vproc) {
> +next_up_step:
> + old_vsram = regulator_get_voltage(sram_reg);
> +
> + vsram = (new_vsram - old_vproc < MAX_VOLT_SHIFT) ?
> + new_vsram : old_vproc + MAX_VOLT_SHIFT;
> + vsram = get_regulator_voltage_floor(sram_reg, vsram);
> +
> + ret = regulator_set_voltage(sram_reg, vsram, vsram);
> + if (ret)
> + return ret;
> +
> + vproc = (new_vsram == vsram) ?
> + new_vproc : vsram - MIN_VOLT_SHIFT;
> + vproc = get_regulator_voltage_ceil(proc_reg, vproc);
> +
> + ret = regulator_set_voltage(proc_reg, vproc, vproc);
> + if (ret) {
> + regulator_set_voltage(sram_reg, old_vsram, old_vsram);
> + return ret;
> + }
> +
> + if (new_vproc == vproc && new_vsram == vsram)
> + return 0;
> +
> + old_vproc = vproc;
> + goto next_up_step;
Perhaps a naive question: but, is this the correct place to do this? I
would expect this stepping behavior to be implemented in the driver
controlling the regulator you are consuming. It seems strange to do it
here.
Josh
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