RE: [PATCH v3 04/11] OMAP3: PM: Adding smartreflex device file.

From: "Gopinath, Thara" <thara@ti.com>
To: Kevin Hilman <khilman@deeprootsystems.com>
Cc: "linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
	"paul@pwsan.com" <paul@pwsan.com>,
	"Cousson, Benoit" <b-cousson@ti.com>,
	"Sripathy, Vishwanath" <vishwanath.bs@ti.com>,
	"Sawant, Anand" <sawant@ti.com>
Subject: RE: [PATCH v3 04/11] OMAP3: PM: Adding smartreflex device file.
Date: Fri, 22 Oct 2010 20:06:47 +0530	[thread overview]
Message-ID: <5A47E75E594F054BAF48C5E4FC4B92AB035EB95EA6@dbde02.ent.ti.com> (raw)
In-Reply-To: <1287084563.14514.155.camel@localhost>

>>-----Original Message-----
>>From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
>>owner@vger.kernel.org] On Behalf Of Kevin Hilman
>>Sent: Friday, October 15, 2010 12:59 AM
>>To: Gopinath, Thara
>>Cc: linux-omap@vger.kernel.org; paul@pwsan.com; Cousson, Benoit; Sripathy,
>>Vishwanath; Sawant, Anand
>>Subject: Re: [PATCH v3 04/11] OMAP3: PM: Adding smartreflex device file.
>>
>>On Wed, 2010-09-22 at 20:15 +0530, Thara Gopinath wrote:
>>> This patch adds support for device registration of various
>>> smartreflex module present in the system. This patch introduces
>>> the platform data for smartreflex devices which include
>>> the efused and test n-target vaules, module enable/disable
>>> pointers and a parameter to indicate whether smartreflex
>>> autocompensation needs to be enabled on init or not.
>>> Currently auocompensation is enabled on init by default
>>> for OMAP3430 ES3.1 chip.
>>>
>>> Signed-off-by: Thara Gopinath <thara@ti.com>
>>> ---
>>>  arch/arm/mach-omap2/Makefile    |    2 +-
>>>  arch/arm/mach-omap2/sr_device.c |  174
>>+++++++++++++++++++++++++++++++++++++++
>>>  2 files changed, 175 insertions(+), 1 deletions(-)
>>>  create mode 100644 arch/arm/mach-omap2/sr_device.c
>>>
>>> diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
>>> index 8dd32a7..abc377a 100644
>>> --- a/arch/arm/mach-omap2/Makefile
>>> +++ b/arch/arm/mach-omap2/Makefile
>>> @@ -56,7 +56,7 @@ obj-$(CONFIG_ARCH_OMAP3)		+= pm34xx.o sleep34xx.o
>>voltage.o \
>>>  					   cpuidle34xx.o pm_bus.o
>>>  obj-$(CONFIG_ARCH_OMAP4)		+= pm44xx.o pm_bus.o
>>>  obj-$(CONFIG_PM_DEBUG)			+= pm-debug.o
>>> -obj-$(CONFIG_OMAP_SMARTREFLEX)          += smartreflex.o
>>> +obj-$(CONFIG_OMAP_SMARTREFLEX)          += sr_device.o smartreflex.o
>>>
>>>  AFLAGS_sleep24xx.o			:=-Wa,-march=armv6
>>>  AFLAGS_sleep34xx.o			:=-Wa,-march=armv7-a
>>> diff --git a/arch/arm/mach-omap2/sr_device.c b/arch/arm/mach-
>>omap2/sr_device.c
>>> new file mode 100644
>>> index 0000000..606da59
>>> --- /dev/null
>>> +++ b/arch/arm/mach-omap2/sr_device.c
>>> @@ -0,0 +1,174 @@
>>> +/*
>>> + * OMAP3/OMAP4 smartreflex device file
>>> + *
>>> + * Author: Thara Gopinath	<thara@ti.com>
>>> + *
>>> + * Based originally on code from smartreflex.c
>>> + * Copyright (C) 2010 Texas Instruments, Inc.
>>> + * Thara Gopinath <thara@ti.com>
>>> + *
>>> + * Copyright (C) 2008 Nokia Corporation
>>> + * Kalle Jokiniemi
>>> + *
>>> + * Copyright (C) 2007 Texas Instruments, Inc.
>>> + * Lesly A M <x0080970@ti.com>
>>> + *
>>> + * 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.
>>> + */
>>> +
>>> +#include <linux/err.h>
>>> +#include <linux/slab.h>
>>> +
>>> +#include <plat/control.h>
>>> +#include <plat/omap_device.h>
>>> +#include <plat/smartreflex.h>
>>> +#include <plat/voltage.h>
>>> +
>>> +static struct omap_device_pm_latency omap_sr_latency[] = {
>>> +	{
>>> +		.deactivate_func = omap_device_idle_hwmods,
>>> +		.activate_func	 = omap_device_enable_hwmods,
>>> +		.flags = OMAP_DEVICE_LATENCY_AUTO_ADJUST
>>> +	},
>>> +};
>>> +
>>> +#ifdef OMAP_SMARTREFLEX_TESTING
>>> +/*
>>> + * Hard coded nvalues for testing purposes for OMAP3430,
>>> + * may cause device to hang!
>>> + */
>>> +static void __init sr_set_nvalues(struct omap_sr_dev_data *dev_data,
>>> +				struct omap_sr_data *sr_data)
>>> +{
>>> +	int i;
>>> +
>>> +	if (!dev_data || !dev_data->volts_supported ||
>>> +			!dev_data->volt_data || !dev_data->test_nvalues) {
>>> +		pr_warning("%s: Bad parameters! dev_data = %x,"
>>> +			"dev_data->volts_supported = %x,"
>>> +			"dev_data->volt_data = %x,"
>>> +			"dev_data->test_nvalues = %x\n", __func__,
>>> +			(unsigned int)dev_data, dev_data->volts_supported,
>>> +			(unsigned int)dev_data->volt_data,
>>> +			(unsigned int)dev_data->test_nvalues);
>>> +		return;
>>> +	}
>>> +
>>> +	sr_data->senn_mod = dev_data->test_sennenable;
>>> +	sr_data->senp_mod = dev_data->test_senpenable;
>>> +	for (i = 0; i < dev_data->volts_supported; i++)
>>> +		dev_data->volt_data[i].sr_nvalue = dev_data->test_nvalues[i];
>>> +}
>>> +#else
>>> +/* Read EFUSE values from control registers for OMAP3430 */
>>> +static void __init sr_set_nvalues(struct omap_sr_dev_data *dev_data,
>>> +				struct omap_sr_data *sr_data)
>>> +{
>>> +	int i;
>>> +
>>> +	if (!dev_data || !dev_data->volts_supported || !dev_data->volt_data ||
>>> +			!dev_data->efuse_nvalues_offs) {
>>> +		pr_warning("%s: Bad parameters! dev_data = %x,"
>>> +			"dev_data->volts_supported = %x,"
>>> +			"dev_data->volt_data = %x,"
>>> +			"dev_data->efuse_nvalues_offs = %x\n", __func__,
>>> +			(unsigned int)dev_data, dev_data->volts_supported,
>>> +			(unsigned int)dev_data->volt_data,
>>> +			(unsigned int)dev_data->efuse_nvalues_offs);
>>> +		return;
>>> +	}
>>> +
>>> +	/*
>>> +	 * From OMAP3630 onwards there are no efuse registers for senn_mod
>>> +	 * and senp_mod. They have to be 0x1 by default.
>>> +	 */
>>> +	if (!dev_data->efuse_sr_control) {
>>> +		sr_data->senn_mod = 0x1;
>>> +		sr_data->senp_mod = 0x1;
>>> +	} else {
>>> +		sr_data->senn_mod =
>>> +				((omap_ctrl_readl(dev_data->efuse_sr_control) &
>>> +				(0x3 << dev_data->sennenable_shift)) >>
>>> +				dev_data->sennenable_shift);
>>> +		sr_data->senp_mod =
>>> +				((omap_ctrl_readl(dev_data->efuse_sr_control) &
>>> +				(0x3 << dev_data->senpenable_shift)) >>
>>> +				dev_data->senpenable_shift);
>>> +	}
>>
>>For readbility, can you do the ctrl_read on one line, then the
>>mask/shift on a separate line, e.g.:
>>
>>		sr_data->senn_mod = omap_ctrl_readl...
>>		sr_data->senn_mod &= ....
>>
>>> +	for (i = 0; i < dev_data->volts_supported; i++)
>>> +		dev_data->volt_data[i].sr_nvalue = omap_ctrl_readl(
>>> +				dev_data->efuse_nvalues_offs[i]);
>>
>>The wrapping here affects readability.  It would be better to do this in
>>two lines:
>>
>>		v = omap_ctrl_readl...
>>		dev_data-... = v;
>>
>>Similar readability problem this part of OMAP4 series.

Will do. 

>>
>>> +}
>>> +#endif
>>> +
>>> +static int sr_dev_init(struct omap_hwmod *oh, void *user)
>>> +{
>>> +	struct omap_sr_data *sr_data;
>>> +	struct omap_sr_dev_data *sr_dev_data;
>>> +	struct omap_device *od;
>>> +	char *name = "smartreflex";
>>> +	static int i;
>>> +
>>> +	sr_data = kzalloc(sizeof(struct omap_sr_data), GFP_KERNEL);
>>> +	if (!sr_data) {
>>> +		pr_err("%s: Unable to allocate memory for %s sr_data.Error!\n",
>>> +			__func__, oh->name);
>>> +		return -ENOMEM;
>>> +	}
>>> +
>>> +	sr_dev_data = (struct omap_sr_dev_data *)oh->dev_attr;
>>> +	if (unlikely(!sr_dev_data)) {
>>> +		pr_err("%s: dev atrribute is NULL\n", __func__);
>>> +		goto exit;
>>> +	}
>>> +
>>> +	/*
>>> +	 * OMAP3430 ES3.1 chips by default come with Efuse burnt
>>> +	 * with parameters required for full functionality of
>>> +	 * smartreflex AVS feature like ntarget values , sennenable
>>> +	 * and senpenable. So enable the SR AVS feature during boot up
>>> +	 * itself if it is a OMAP3430 ES3.1 chip.
>>> +	 */
>>> +	sr_data->enable_on_init = false;
>>> +	if (cpu_is_omap343x()) {
>>> +		if (omap_rev() == OMAP3430_REV_ES3_1)
>>> +			sr_data->enable_on_init = true;
>>> +	}
>>
>>The braces are not needed here.

Ok

>>
>>> +	sr_data->voltdm = omap_voltage_domain_get(sr_dev_data->vdd_name);
>>> +	if (IS_ERR(sr_data->voltdm)) {
>>> +		pr_err("%s: Unable to get voltage domain pointer for VDD %s\n",
>>> +			__func__, sr_dev_data->vdd_name);
>>> +		goto exit;
>>> +	}
>>> +
>>> +	sr_dev_data->volts_supported = omap_voltage_get_volttable(
>>> +			sr_data->voltdm, &sr_dev_data->volt_data);
>>>
>>> +	if (!sr_dev_data->volts_supported) {
>>> +		pr_warning("%s: No Voltage table registerd fo VDD%d."
>>> +			"Something really wrong\n\n", __func__, i + 1);
>>> +		goto exit;
>>> +	}
>>> +
>>> +	sr_set_nvalues(sr_dev_data, sr_data);
>>
>>First question: why does this N-value init need to be done in the device
>>init?  It seems better to be a part of the SR driver probe.

OMAP3 and OMAP4 has different ways of reading the efuse registers. I would like it to be in device file so that we can have the necessary checks. The driver should not be bothered about getting of the n-values.

>>
>>Second, this section took me quite some time to understand, as it seems
>>to blur the lines of device and driver but also how it interacts with
>>the voltage layer.
>>
>>sr_set_nvalues() is directly manipulating structures that are internal
>>to the voltage layer.  It also makes assumptions about the ordering of
>>volt_data structs in the voltage layer.
>>
>>Strictly speaking neither the sr_nvalue or sr_errminlimit fields of
>>volt_data are not used at all in the voltage layer, but only in the SR
>>layer, so ideally they should really stay in the SR layer.
>>
>>I think what is needed here is a cleaner way for the SR layer to connect
>>the N-values to a voltage.  The current method of manipulating voltage
>>layer structs inside the SR layer is not acceptable.  Since the n-values
>>are fixed in HW (per SoC), what I suggest is simply having a field like
>>'efuse_id' or something in volt_data.  Then, the smart reflex layer can
>>lookup and index all the efuse values during probe, and when sr_enable
>>is called, it looks up the nvalue based on efuse_id.
>>
>>I assume that the sr_errminlimit could also be set based on efuse_id,
>>and therefore remain contained within the SR layer, but I'm not sure I
>>like that idea any better than keeping it inside volt_data.  For now,
>>I'll let you make the call on errminlimit, but I really want to see the
>>N-value stuff isolated in the SR layer.

I do not understand your proposal here? What kind of variable is efuse-id??

>>
>>Kevin
>>
>>> +	od = omap_device_build(name, i, oh, sr_data, sizeof(*sr_data),
>>> +			       omap_sr_latency,
>>> +			       ARRAY_SIZE(omap_sr_latency), 0);
>>> +	if (IS_ERR(od))
>>> +		pr_warning("%s: Could not build omap_device for %s: %s.\n\n",
>>> +			__func__, name, oh->name);
>>> +exit:
>>> +	i++;
>>> +	kfree(sr_data);
>>> +	return 0;
>>> +}
>>> +
>>> +static int __init omap_devinit_smartreflex(void)
>>> +{
>>> +	return omap_hwmod_for_each_by_class("smartreflex", sr_dev_init, NULL);
>>> +}
>>> +device_initcall(omap_devinit_smartreflex);
>>
>>
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