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Date: Wed, 31 Oct 2012 06:45:08 +0000
From: "R, Durgadoss" <durgadoss.r@...el.com>
To: Jonghwa Lee <jonghwa3.lee@...sung.com>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Brown, Len" <len.brown@...el.com>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Amit Dinel Kachhap <amit.kachhap@...aro.org>
Subject: RE: [PATCH v2] Thermal: exynos: Add sysfs node supporting exynos's
emulation mode.
Hi,
Looks like a nice feature :-)
Without something like this, we had been spending time on
writing test drivers, to actually test our thermal framework code.
BTW, against which tree this patch was generated ?
Rui's -next or master or Linux-next ?
Some comments below, on a quick glance..
> -----Original Message-----
> From: Jonghwa Lee [mailto:jonghwa3.lee@...sung.com]
> Sent: Wednesday, October 31, 2012 9:49 AM
> To: linux-pm@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org; Brown, Len; R, Durgadoss; Rafael J.
> Wysocki; Amit Dinel Kachhap; Jonghwa Lee
> Subject: [PATCH v2] Thermal: exynos: Add sysfs node supporting exynos's
> emulation mode.
>
> This patch supports exynos's emulation mode with newly created sysfs node.
> Exynos 4x12 (4212, 4412) and 5 series provide emulation mode for thermal
> management unit. Thermal emulation mode supports software debug for
> TMU's
> operation. User can set temperature manually with software code and TMU
> will read current temperature from user value not from sensor's value.
> This patch includes also documentary placed under
> Documentation/thermal/.
>
> Signed-off-by: Jonghwa Lee <jonghwa3.lee@...sung.com>
> ---
> v2
> exynos_thermal.c
> - Fix build error occured by wrong emulation control register name.
> - Remove exynos5410 dependent codes.
> exynos_theraml_emulation
> - Align indentation.
>
> Documentation/thermal/exynos_thermal_emulation | 49 +++++++++++++
> drivers/thermal/Kconfig | 9 +++
> drivers/thermal/exynos_thermal.c | 88
> ++++++++++++++++++++++++
> 3 files changed, 146 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/thermal/exynos_thermal_emulation
>
> diff --git a/Documentation/thermal/exynos_thermal_emulation
> b/Documentation/thermal/exynos_thermal_emulation
> new file mode 100644
> index 0000000..062d867
> --- /dev/null
> +++ b/Documentation/thermal/exynos_thermal_emulation
> @@ -0,0 +1,49 @@
> +EXYNOS EMULATION MODE
> +========================
> +
> +Copyright (C) 2012 Samsung Electronics
> +
> +Writen by Jonghwa Lee <jonghwa3.lee@...sung.com>
> +
> +Description
> +-----------
> +
> +Exynos 4x12 (4212, 4412) and 5 series provide emulation mode for thermal
> management unit.
> +Thermal emulation mode supports software debug for TMU's operation.
> User can set temperature
> +manually with software code and TMU will read current temperature from
> user value not from
> +sensor's value.
> +
> +Enabling CONFIG_EXYNOS_THERMAL_EMUL option will make this support
> in available.
> +When it's enabled, sysfs node will be created under
> +/sys/bus/platform/devices/'exynos device name'/ with name of
> 'emulation'.
> +
> +The sysfs node, 'emulation', will contain value 0 for the initial state. When
> you input any
> +temperature you want to update to sysfs node, it automatically enable
> emulation mode and
> +current temperature will be changed into it.
> +(Exynos also supports user changable delay time which would be used to
> delay of
> + changing temperature. However, this node only uses same delay of real
> sensing time, 938us.)
> +
> +Disabling emulation mode only requires writing value 0 to sysfs node.
> +
> +
> +TEMP 120 |
> + |
> + 100 |
> + |
> + 80 |
> + | +-----------
> + 60 | | |
> + | +-------------| |
> + 40 | | | |
> + | | | |
> + 20 | | | +----------
> + | | | | |
> + 0
> |______________|_____________|__________|__________|_______
> __
> + A A A A TIME
> + |<----->| |<----->| |<----->| |
> + | 938us | | | | | |
> +emulation : 0 50 | 70 | 20 | 0
> +current temp : sensor 50 70 20 sensor
Thanks for the documentation. Is there a publicly available data sheet for this?
If so, please provide the link here.
> +
> +
> +
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index e1cb6bd..c02a66c 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -55,3 +55,12 @@ config EXYNOS_THERMAL
> help
> If you say yes here you get support for TMU (Thermal Managment
> Unit) on SAMSUNG EXYNOS series of SoC.
> +
> +config EXYNOS_THERMAL_EMUL
> + bool "EXYNOS TMU emulation mode support"
> + depends on !CPU_EXYNOS4210 && EXYNOS_THERMAL
> + help
> + Exynos 4412 and 4414 and 5 series has emulation mode on TMU.
> + Enable this option will be make sysfs node in exynos thermal
> platform
> + device directory to support emulation mode. With emulation mode
> sysfs
> + node, you can manually input temperature to TMU for simulation
> purpose.
> diff --git a/drivers/thermal/exynos_thermal.c
> b/drivers/thermal/exynos_thermal.c
> index fd03e85..9e3c150 100644
> --- a/drivers/thermal/exynos_thermal.c
> +++ b/drivers/thermal/exynos_thermal.c
> @@ -99,6 +99,15 @@
> #define IDLE_INTERVAL 10000
> #define MCELSIUS 1000
>
> +#ifdef CONFIG_EXYNOS_THERMAL_EMUL
> +#define EXYNOS_EMUL_TIME 0x57F0
> +#define EXYNOS_EMUL_TIME_SHIFT 16
> +#define EXYNOS_EMUL_DATA_SHIFT 8
> +#define EXYNOS_EMUL_DATA_MASK 0xFF
> +#define EXYNOS_EMUL_DISABLE 0x0
> +#define EXYNOS_EMUL_ENABLE 0x1
> +#endif /* CONFIG_EXYNOS_THERMAL_EMUL */
> +
> /* CPU Zone information */
> #define PANIC_ZONE 4
> #define WARN_ZONE 3
> @@ -832,6 +841,82 @@ static inline struct exynos_tmu_platform_data
> *exynos_get_driver_data(
> return (struct exynos_tmu_platform_data *)
> platform_get_device_id(pdev)->driver_data;
> }
> +
> +#ifdef CONFIG_EXYNOS_THERMAL_EMUL
> +static ssize_t exynos_tmu_emulation_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct platform_device *pdev = container_of(dev,
> + struct platform_device, dev);
> + struct exynos_tmu_data *data = platform_get_drvdata(pdev);
> + unsigned int reg;
> + u8 temp_code;
> + int temp, enable;
> +
> + mutex_lock(&data->lock);
> + clk_enable(data->clk);
> + reg = readl(data->base + EXYNOS_EMUL_CON);
> + clk_disable(data->clk);
> + mutex_unlock(&data->lock);
> +
> + enable = reg & EXYNOS_EMUL_ENABLE;
Looks like we don't need this variable 'enable'.
Also, initialize temp to 0 in the beginning, which will save the
else part of the code.
> +
> + if (enable) {
> + reg >>= EXYNOS_EMUL_DATA_SHIFT;
> + temp_code = reg & EXYNOS_EMUL_DATA_MASK;
> + temp = code_to_temp(data, temp_code);
> + } else {
> + temp = 0;
> + }
> +
> + return sprintf(buf, "%d\n", temp);
> +}
> +
> +static ssize_t exynos_tmu_emulation_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct platform_device *pdev = container_of(dev,
> + struct platform_device, dev);
> + struct exynos_tmu_data *data = platform_get_drvdata(pdev);
> + unsigned int reg;
> + u8 temp_code;
> + int temp, enable, i;
> +
> + if (!sscanf(buf, "%d\n", &temp))
> + return -EINVAL;
> +
> + if (temp < 0)
> + return -EINVAL;
Why not combine both the if s using || ?
> +
> + mutex_lock(&data->lock);
> + clk_enable(data->clk);
> +
> + reg = readl(data->base + EXYNOS_EMUL_CON);
> + enable = reg & EXYNOS_EMUL_ENABLE;
> + if (!enable && !temp)
> + goto out;
I think you what you are trying to do here is this:
If the emulation is already disabled, and 'this' write tries to
disable it again, you jump to 'out' as an optimization.
Please correct me if I am wrong.
In this case, name the variable is_enabled or something like
that, which makes the check more explicit.
> +
> + temp_code = (reg >> EXYNOS_EMUL_DATA_SHIFT) &
> EXYNOS_EMUL_DATA_MASK;
> + temp_code = temp == 0 ? temp_code : temp_to_code(data, temp);
> +
> + reg = (EXYNOS_EMUL_TIME << EXYNOS_EMUL_TIME_SHIFT) |
> + (temp_code << EXYNOS_EMUL_DATA_SHIFT) |
> + (temp > 0 ? EXYNOS_EMUL_ENABLE :
> EXYNOS_EMUL_DISABLE);
2 things here:
1. Can we make the temp > 0 comparison as a separate statement, so that
it is easy to read/maintain ?
2. you are comparing temp > 0 here, but above you return when temp < 0.
Looks like, in this case, the flow will never reach here, when temp < 0.
> +
> + writel(reg, data->base + EXYNOS_EMUL_CON);
> +out:
> + clk_disable(data->clk);
> + mutex_unlock(&data->lock);
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR(emulation, 0644, exynos_tmu_emulation_show,
> + exynos_tmu_emulation_store);
> +#endif
> +
> static int __devinit exynos_tmu_probe(struct platform_device *pdev)
> {
> struct exynos_tmu_data *data;
> @@ -930,6 +1015,9 @@ static int __devinit exynos_tmu_probe(struct
> platform_device *pdev)
> dev_err(&pdev->dev, "Failed to register thermal
> interface\n");
> goto err_clk;
> }
> +#ifdef CONFIG_EXYNOS_THERMAL_EMUL
> + device_create_file(&pdev->dev, &dev_attr_emulation);
Don't we want to capture the return value here ?
Also, if we conditionally create this, we should remove this conditionally also.
I did not see a corresponding device_remove_file for this attr.
> +#endif
Can we club all the code inside CONFIG_*_EMUL at one place ?
This will make it neat, and not spread the #ifdefs all over the driver.
Thanks,
Durga
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