-----Original Message-----
From: amit.kucheria at verdurent.com <redacted> On
Behalf Of Amit Kucheria
Sent: Wednesday, May 16, 2018 16:13
To: Ilia Lin <redacted>
Cc: Michael Turquette <mturquette@baylibre.com>; sboyd at kernel.org; Rob
Herring [off-list ref]; Mark Rutland [off-list ref]; Viresh
Kumar [off-list ref]; nm at ti.com; lgirdwood at gmail.com;
broonie at kernel.org; Andy Gross [off-list ref]; David Brown
[off-list ref]; catalin.marinas at arm.com;
will.deacon at arm.com; Rafael J. Wysocki [off-list ref]; linux-
clk at vger.kernel.org; devicetree at vger.kernel.org; LKML <linux-
kernel at vger.kernel.org>; Linux PM list [off-list ref]; linux-
arm-msm at vger.kernel.org; linux-soc at vger.kernel.org; lakml <linux-arm-
kernel at lists.infradead.org>; Rajendra Nayak [off-list ref];
nicolas.dechesne at linaro.org; celster at codeaurora.org;
tfinkel at codeaurora.org
Subject: Re: [PATCH v7 12/14] cpufreq: Add Kryo CPU scaling driver

On Tue, May 15, 2018 at 12:13 PM, Ilia Lin [off-list ref] wrote:

quoted

In Certain QCOM SoCs like apq8096 and msm8996 that have KRYO
processors, the CPU ferequencies subset and voltage value of each OPP
varies

s/ferequencies/frequency

quoted

based on the silicon variant in use. Qualcomm Process Voltage Scaling
Tables defines the voltage and frequency value based on the msm-id in
SMEM and speedbin blown in the efuse combination.
The qcom-cpufreq-kryo driver reads the msm-id and efuse value from the
SoC to provide the OPP framework with required information.
This is used to determine the voltage and frequency value for each OPP
of
operating-points-v2 table when it is parsed by the OPP framework.

Signed-off-by: Ilia Lin <redacted>
---
 drivers/cpufreq/Kconfig.arm          |  11 +++
 drivers/cpufreq/Makefile             |   1 +
 drivers/cpufreq/cpufreq-dt-platdev.c |   3 +
 drivers/cpufreq/qcom-cpufreq-kryo.c  | 150
+++++++++++++++++++++++++++++++++++
 4 files changed, 165 insertions(+)
 create mode 100644 drivers/cpufreq/qcom-cpufreq-kryo.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index de55c7d..5c16f05 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm

@@ -124,6 +124,17 @@ config ARM_OMAP2PLUS_CPUFREQ
        depends on ARCH_OMAP2PLUS
        default ARCH_OMAP2PLUS

+config ARM_QCOM_CPUFREQ_KRYO
+       bool "Qualcomm Technologies, Inc. Kryo based CPUFreq"

"Qualcomm Kryo CPUFreq support" should be enough. Kconfig isn't the place
for Trademark compliance :-)

This is mandatory requirement of the QTIs legal.

quoted

+       depends on QCOM_QFPROM
+       depends on QCOM_SMEM
+       select PM_OPP
+       help
+         This adds the CPUFreq driver for
+         Qualcomm Technologies, Inc. Kryo SoC based boards.
+
+         If in doubt, say N.
+
 config ARM_S3C_CPUFREQ
        bool
        help

diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile index

8d24ade..fb4a2ec 100644

--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile

@@ -65,6 +65,7 @@ obj-$(CONFIG_MACH_MVEBU_V7)           += mvebu-

cpufreq.o

quoted

 obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ)    += omap-cpufreq.o
 obj-$(CONFIG_ARM_PXA2xx_CPUFREQ)       += pxa2xx-cpufreq.o
 obj-$(CONFIG_PXA3xx)                   += pxa3xx-cpufreq.o
+obj-$(CONFIG_ARM_QCOM_CPUFREQ_KRYO)    += qcom-cpufreq-kryo.o
 obj-$(CONFIG_ARM_S3C2410_CPUFREQ)      += s3c2410-cpufreq.o
 obj-$(CONFIG_ARM_S3C2412_CPUFREQ)      += s3c2412-cpufreq.o
 obj-$(CONFIG_ARM_S3C2416_CPUFREQ)      += s3c2416-cpufreq.o

diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c

b/drivers/cpufreq/cpufreq-dt-platdev.c
index 3b585e4..77d6ab8 100644

--- a/drivers/cpufreq/cpufreq-dt-platdev.c
+++ b/drivers/cpufreq/cpufreq-dt-platdev.c

@@ -118,6 +118,9 @@

        { .compatible = "nvidia,tegra124", },

+       { .compatible = "qcom,apq8096", },
+       { .compatible = "qcom,msm8996", },
+
        { .compatible = "st,stih407", },
        { .compatible = "st,stih410", },

diff --git a/drivers/cpufreq/qcom-cpufreq-kryo.c

b/drivers/cpufreq/qcom-cpufreq-kryo.c
new file mode 100644
index 0000000..10d7236

--- /dev/null
+++ b/drivers/cpufreq/qcom-cpufreq-kryo.c

@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0
+/*

Stray space here.

quoted

+ * Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only 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/cpu.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/slab.h>
+#include <linux/soc/qcom/smem.h>
+
+#define MSM_ID_SMEM    137
+#define SILVER_LEAD    0
+#define GOLD_LEAD      2
+
+enum _msm_id {
+       MSM8996V3 = 0xF6ul,
+       APQ8096V3 = 0x123ul,
+       MSM8996SG = 0x131ul,
+       APQ8096SG = 0x138ul,
+};
+
+enum _msm8996_version {
+       MSM8996_V3,
+       MSM8996_SG,
+       NUM_OF_MSM8996_VERSIONS,
+};
+
+static enum _msm8996_version __init
+qcom_cpufreq_kryo_get_msm_id(void)
+{
+       size_t len;
+       u32 *msm_id;
+       enum _msm8996_version version;
+
+       msm_id = qcom_smem_get(QCOM_SMEM_HOST_ANY,

MSM_ID_SMEM, &len);

quoted

+       /* The first 4 bytes are format, next to them is the actual msm-id */
+       msm_id++;
+
+       switch ((enum _msm_id)*msm_id) {
+       case MSM8996V3:
+       case APQ8096V3:
+               version = MSM8996_V3;
+               break;
+       case MSM8996SG:
+       case APQ8096SG:
+               version = MSM8996_SG;
+               break;
+       default:
+               version = NUM_OF_MSM8996_VERSIONS;
+       }
+
+       return version;
+}
+
+static int __init qcom_cpufreq_kryo_driver_init(void)
+{
+       size_t len;
+       int ret;
+       u32 versions;
+       enum _msm8996_version msm8996_version;
+       u8 *speedbin;
+       struct device *cpu_dev;
+       struct device_node *np;
+       struct nvmem_cell *speedbin_nvmem;
+       struct opp_table *opp_temp = NULL;
+
+       cpu_dev = get_cpu_device(SILVER_LEAD);
+       if (IS_ERR_OR_NULL(cpu_dev))
+               return PTR_ERR(cpu_dev);
+
+       msm8996_version = qcom_cpufreq_kryo_get_msm_id();
+       if (NUM_OF_MSM8996_VERSIONS == msm8996_version) {
+               dev_err(cpu_dev, "Not Snapdragon 820/821!");
+               return -ENODEV;
+        }

Use tab instead of spaces.

quoted

+
+       np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
+       if (IS_ERR_OR_NULL(np))
+               return PTR_ERR(np);
+
+       if (!of_device_is_compatible(np, "operating-points-v2-kryo-cpu")) {
+               ret = -ENOENT;
+               goto free_np;
+       }
+
+       speedbin_nvmem = of_nvmem_cell_get(np, NULL);
+       if (IS_ERR(speedbin_nvmem)) {
+               ret = PTR_ERR(speedbin_nvmem);
+               dev_err(cpu_dev, "Could not get nvmem cell: %d\n", ret);
+               goto free_np;
+       }
+
+       speedbin = nvmem_cell_read(speedbin_nvmem, &len);
+
+       switch (msm8996_version) {
+       case MSM8996_V3:
+               versions = 1 << (unsigned int)(*speedbin);
+               break;
+       case MSM8996_SG:
+               versions = 1 << ((unsigned int)(*speedbin) + 4);
+               break;
+       default:
+               BUG();
+               break;
+       }
+
+       ret = PTR_ERR_OR_ZERO(opp_temp =
+                             dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
+       if (0 > ret)

Any particular reason to prefer this over (ret < 0) that is generally used? I've
seen it used to avoid the == vs. = typos, but not for other comparisons.

Suggest sticking to what is commonly used i.e. ret < 0.

quoted

+               goto free_opp;
+
+       cpu_dev = get_cpu_device(GOLD_LEAD);

Error check cpu_dev here?

quoted

+       ret = PTR_ERR_OR_ZERO(opp_temp =
+                             dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
+       if (0 > ret)
+               goto free_opp;
+
+
+       ret = PTR_ERR_OR_ZERO(platform_device_register_simple("cpufreq-

dt",

quoted

+                                                             -1,
+ NULL, 0));
+
+       if (0 == ret)
+               return 0;
+
+free_opp:
+       dev_pm_opp_put_supported_hw(opp_temp);

This is not needed because dev_pm_opp_set_supported_hw will free
memory in case of failure. This call in only needed in case of a successful get.

quoted

+
+free_np:
+       of_node_put(np);
+       return ret;

Suggest something like this instead:

.
.

opp_temp = dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
if (IS_ERR(opp_temp)) {
     dev_err(cpu_dev, "Failed to set supported hardware\n");
     ret = PTR_ERR(opp_temp);
    goto free_np;
}

cpu_dev = get_cpu_device(GOLD_LEAD);

opp_temp = dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
if (IS_ERR(opp_temp)) {
     dev_err(cpu_dev, "Failed to set supported hardware\n");
     ret = PTR_ERR(opp_temp);
    goto free_np;
}

ret =  platform_device_register_simple("cpufreq-dt", -1, NULL, 0));

if (!IS_ERR_OR_NULL(ret))
     goto out;

free_np:
     of_node_put(np);
out:
     return ret;

quoted

+}
+late_initcall(qcom_cpufreq_kryo_driver_init);
+
+MODULE_DESCRIPTION("Qualcomm Technologies, Inc. Kryo CPUfreq
+driver"); MODULE_LICENSE("GPL v2");
--
1.9.1