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Date:   Fri, 22 Feb 2019 00:13:59 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Bjorn Andersson <bjorn.andersson@linaro.org>
Cc:     Vaishali Thakkar <vaishali.thakkar@linaro.org>,
        andy.gross@linaro.org, david.brown@linaro.org,
        gregkh@linuxfoundation.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, rafael@kernel.org, vkoul@kernel.org
Subject: Re: [PATCH v2 3/5] soc: qcom: socinfo: Expose custom attributes
Message-ID: <20190221221359.GD3485@pendragon.ideasonboard.com>
References: <20190220045829.6852-1-vaishali.thakkar@linaro.org>
 <20190221121841.GA32108@pendragon.ideasonboard.com>
 <20190221155742.GD2122@tuxbook-pro>
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In-Reply-To: <20190221155742.GD2122@tuxbook-pro>
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Hi Bjorn,

On Thu, Feb 21, 2019 at 07:57:42AM -0800, Bjorn Andersson wrote:
> On Thu 21 Feb 04:18 PST 2019, Laurent Pinchart wrote:
> 
> > Hi Vaishali,
> > 
> > Thank you for the patch.
> > 
> > On Wed, Feb 20, 2019 at 10:28:29AM +0530, Vaishali Thakkar wrote:
> > > The Qualcomm socinfo provides a number of additional attributes,
> > > add these to the socinfo driver and expose them via debugfs
> > > functionality.
> > 
> > What is the use case for these attributes ? I fear they will be used in
> > production systems, and that would require debugfs in production, which
> > isn't a good idea. If you need to expose those attributes for anything
> > else than debugging then we need a proper API, likely sysfs-based.
> 
> The use case of these attributes, beyond development/debugging, are
> unfortunately somewhat unknown and is the reason why they where moved to
> debugfs from the earlier attempts to upstream this.
> 
> I think the production requirements at hand prohibits debugfs to be
> present, so attributes that are required beyond development/debugging
> purposes would have to be migrated out to sysfs - but the idea here is
> that such migration would have come with the missing motivation to add
> them there today.

If the use case is just debug/development, would it be enough to print
this information in the kernel log at boot time ? I may be a bit
paranoid, but I always worry about API abuse :-(

> > > Signed-off-by: Vaishali Thakkar <vaishali.thakkar@linaro.org>
> > > ---
> > > Changes since v1:
> > > 	- Remove unnecessary debugfs dir creation check
> > > 	- Align ifdefs to left
> > > 	- Fix function signatures for debugfs init/exit
> > > ---
> > >  drivers/soc/qcom/socinfo.c | 198 +++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 198 insertions(+)
> > > 
> > > diff --git a/drivers/soc/qcom/socinfo.c b/drivers/soc/qcom/socinfo.c
> > > index 02078049fac7..5f4bef216ae1 100644
> > > --- a/drivers/soc/qcom/socinfo.c
> > > +++ b/drivers/soc/qcom/socinfo.c
> > > @@ -4,6 +4,7 @@
> > >   * Copyright (c) 2017-2019, Linaro Ltd.
> > >   */
> > >  
> > > +#include <linux/debugfs.h>
> > >  #include <linux/err.h>
> > >  #include <linux/module.h>
> > >  #include <linux/platform_device.h>
> > > @@ -29,6 +30,28 @@
> > >   */
> > >  #define SMEM_HW_SW_BUILD_ID            137
> > >  
> > > +#ifdef CONFIG_DEBUG_FS
> > > +/* pmic model info */
> > > +static const char *const pmic_model[] = {
> > > +	[0]  = "Unknown PMIC model",
> > > +	[9]  = "PM8994",
> > > +	[11] = "PM8916",
> > > +	[13] = "PM8058",
> > > +	[14] = "PM8028",
> > > +	[15] = "PM8901",
> > > +	[16] = "PM8027",
> > > +	[17] = "ISL9519",
> > > +	[18] = "PM8921",
> > > +	[19] = "PM8018",
> > > +	[20] = "PM8015",
> > > +	[21] = "PM8014",
> > > +	[22] = "PM8821",
> > > +	[23] = "PM8038",
> > > +	[24] = "PM8922",
> > > +	[25] = "PM8917",
> > > +};
> > > +#endif /* CONFIG_DEBUG_FS */
> > > +
> > >  /* Socinfo SMEM item structure */
> > >  struct socinfo {
> > >  	__le32 fmt;
> > > @@ -70,6 +93,10 @@ struct socinfo {
> > >  struct qcom_socinfo {
> > >  	struct soc_device *soc_dev;
> > >  	struct soc_device_attribute attr;
> > > +#ifdef CONFIG_DEBUG_FS
> > > +	struct dentry *dbg_root;
> > > +#endif /* CONFIG_DEBUG_FS */
> > > +	struct socinfo *socinfo;
> > >  };
> > >  
> > >  struct soc_of_id {
> > > @@ -133,6 +160,171 @@ static const char *socinfo_machine(struct device *dev, unsigned int id)
> > >  	return NULL;
> > >  }
> > >  
> > > +#ifdef CONFIG_DEBUG_FS
> > > +
> > > +#define UINT_SHOW(name, attr)						\
> > > +static int qcom_show_##name(struct seq_file *seq, void *p)		\
> > > +{									\
> > > +	struct socinfo *socinfo = seq->private;				\
> > > +	seq_printf(seq, "%u\n", le32_to_cpu(socinfo->attr));		\
> > > +	return 0;							\
> > > +}									\
> > > +static int qcom_open_##name(struct inode *inode, struct file *file)	\
> > > +{									\
> > > +	return single_open(file, qcom_show_##name, inode->i_private);	\
> > > +}									\
> > > +									\
> > > +static const struct file_operations qcom_ ##name## _ops = {		\
> > > +	.open = qcom_open_##name,					\
> > > +	.read = seq_read,						\
> > > +	.llseek = seq_lseek,						\
> > > +	.release = single_release,					\
> > > +}
> > > +
> > > +#define DEBUGFS_UINT_ADD(name)						\
> > > +	debugfs_create_file(__stringify(name), 0400,			\
> > > +			    qcom_socinfo->dbg_root,			\
> > > +			    qcom_socinfo->socinfo, &qcom_ ##name## _ops)
> > > +
> > > +#define HEX_SHOW(name, attr)						\
> > > +static int qcom_show_##name(struct seq_file *seq, void *p)		\
> > > +{									\
> > > +	struct socinfo *socinfo = seq->private;				\
> > > +	seq_printf(seq, "0x%x\n", le32_to_cpu(socinfo->attr));		\
> > > +	return 0;							\
> > > +}									\
> > > +static int qcom_open_##name(struct inode *inode, struct file *file)	\
> > > +{									\
> > > +	return single_open(file, qcom_show_##name, inode->i_private);	\
> > > +}									\
> > > +									\
> > > +static const struct file_operations qcom_ ##name## _ops = {		\
> > > +	.open = qcom_open_##name,					\
> > > +	.read = seq_read,						\
> > > +	.llseek = seq_lseek,						\
> > > +	.release = single_release,					\
> > > +}
> > > +
> > > +#define DEBUGFS_HEX_ADD(name)						\
> > > +	debugfs_create_file(__stringify(name), 0400,			\
> > > +			    qcom_socinfo->dbg_root,			\
> > > +			    qcom_socinfo->socinfo, &qcom_ ##name## _ops)
> > > +
> > > +
> > > +#define QCOM_OPEN(name, _func)						\
> > > +static int qcom_open_##name(struct inode *inode, struct file *file)	\
> > > +{									\
> > > +	return single_open(file, _func, inode->i_private);		\
> > > +}									\
> > > +									\
> > > +static const struct file_operations qcom_ ##name## _ops = {		\
> > > +	.open = qcom_open_##name,					\
> > > +	.read = seq_read,						\
> > > +	.llseek = seq_lseek,						\
> > > +	.release = single_release,					\
> > > +}
> > > +
> > > +#define DEBUGFS_ADD(name)						\
> > > +	debugfs_create_file(__stringify(name), 0400,			\
> > > +			    qcom_socinfo->dbg_root,			\
> > > +			    qcom_socinfo->socinfo, &qcom_ ##name## _ops)
> > > +
> > > +
> > > +static int qcom_show_build_id(struct seq_file *seq, void *p)
> > > +{
> > > +	struct socinfo *socinfo = seq->private;
> > > +
> > > +	seq_printf(seq, "%s\n", socinfo->build_id);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int qcom_show_accessory_chip(struct seq_file *seq, void *p)
> > > +{
> > > +	struct socinfo *socinfo = seq->private;
> > > +
> > > +	seq_printf(seq, "%d\n", le32_to_cpu(socinfo->accessory_chip));
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int qcom_show_platform_subtype(struct seq_file *seq, void *p)
> > > +{
> > > +	struct socinfo *socinfo = seq->private;
> > > +	int subtype = le32_to_cpu(socinfo->hw_plat_subtype);
> > > +
> > > +	if (subtype < 0)
> > > +		return -EINVAL;
> > > +
> > > +	seq_printf(seq, "%u\n", subtype);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int qcom_show_pmic_model(struct seq_file *seq, void *p)
> > > +{
> > > +	struct socinfo *socinfo = seq->private;
> > > +	int model = SOCINFO_MINOR(le32_to_cpu(socinfo->pmic_model));
> > > +
> > > +	if (model < 0)
> > > +		return -EINVAL;
> > > +
> > > +	seq_printf(seq, "%s\n", pmic_model[model]);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int qcom_show_pmic_die_revision(struct seq_file *seq, void *p)
> > > +{
> > > +	struct socinfo *socinfo = seq->private;
> > > +
> > > +	seq_printf(seq, "%u.%u\n",
> > > +		   SOCINFO_MAJOR(le32_to_cpu(socinfo->pmic_die_rev)),
> > > +		   SOCINFO_MINOR(le32_to_cpu(socinfo->pmic_die_rev)));
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +UINT_SHOW(raw_version, raw_ver);
> > > +UINT_SHOW(hardware_platform, hw_plat);
> > > +UINT_SHOW(platform_version, plat_ver);
> > > +UINT_SHOW(foundry_id, foundry_id);
> > > +HEX_SHOW(chip_family, chip_family);
> > > +HEX_SHOW(raw_device_family, raw_device_family);
> > > +HEX_SHOW(raw_device_number, raw_device_num);
> > > +QCOM_OPEN(build_id, qcom_show_build_id);
> > > +QCOM_OPEN(accessory_chip, qcom_show_accessory_chip);
> > > +QCOM_OPEN(pmic_model, qcom_show_pmic_model);
> > > +QCOM_OPEN(platform_subtype, qcom_show_platform_subtype);
> > > +QCOM_OPEN(pmic_die_revision, qcom_show_pmic_die_revision);
> > > +
> > > +static void socinfo_debugfs_init(struct qcom_socinfo *qcom_socinfo)
> > > +{
> > > +	qcom_socinfo->dbg_root = debugfs_create_dir("qcom_socinfo", NULL);
> > > +
> > > +	DEBUGFS_UINT_ADD(raw_version);
> > > +	DEBUGFS_UINT_ADD(hardware_platform);
> > > +	DEBUGFS_UINT_ADD(platform_version);
> > > +	DEBUGFS_UINT_ADD(foundry_id);
> > > +	DEBUGFS_HEX_ADD(chip_family);
> > > +	DEBUGFS_HEX_ADD(raw_device_family);
> > > +	DEBUGFS_HEX_ADD(raw_device_number);
> > > +	DEBUGFS_ADD(build_id);
> > > +	DEBUGFS_ADD(accessory_chip);
> > > +	DEBUGFS_ADD(pmic_model);
> > > +	DEBUGFS_ADD(platform_subtype);
> > > +	DEBUGFS_ADD(pmic_die_revision);
> > > +}
> > > +
> > > +static void socinfo_debugfs_exit(struct qcom_socinfo *qcom_socinfo)
> > > +{
> > > +	debugfs_remove_recursive(qcom_socinfo->dbg_root);
> > > +}
> > > +#else
> > > +static void socinfo_debugfs_init(struct qcom_socinfo *qcom_socinfo) { return 0; }
> > > +static void socinfo_debugfs_exit(struct qcom_socinfo *qcom_socinfo) {  }
> > > +#endif /* CONFIG_DEBUG_FS */
> > > +
> > >  static int qcom_socinfo_probe(struct platform_device *pdev)
> > >  {
> > >  	struct qcom_socinfo *qs;
> > > @@ -165,6 +357,10 @@ static int qcom_socinfo_probe(struct platform_device *pdev)
> > >  	if (IS_ERR(qs->soc_dev))
> > >  		return PTR_ERR(qs->soc_dev);
> > >  
> > > +	qs->socinfo = info;
> > > +
> > > +	socinfo_debugfs_init(qs);
> > > +
> > >  	/* Feed the soc specific unique data into entropy pool */
> > >  	add_device_randomness(info, item_size);
> > >  
> > > @@ -179,6 +375,8 @@ static int qcom_socinfo_remove(struct platform_device *pdev)
> > >  
> > >  	soc_device_unregister(qs->soc_dev);
> > >  
> > > +	socinfo_debugfs_exit(qs);
> > > +
> > >  	return 0;
> > >  }
> > > 

-- 
Regards,

Laurent Pinchart