[PATCH v2] add mdio bus support to miitool

[PATCH v2] add mdio bus support to miitool

[Sascha Hauer]

2nd version. This adds both the mdio buses and the phy devices
to the mdio_bus_type. This is in sync with Linux which also
adds the buses (for example i2c_adapter) and the devices (for example
i2c devices) to the same bus type. Linux uses a struct device_type
pointer in struct device to distinguish between both. As we do
not have this struct, we use the type_data field which has the
same purpose.

----------------------------------------------------------------
Sascha Hauer (2):
      net phy: Add mdio buses to mdio_bus_type
      miitool: Add support for examing mdio bus

 commands/miitool.c         |   94 +++++++++++++++++++++++++++++++++++---------
 drivers/net/phy/mdio_bus.c |   18 +++++++++
 drivers/net/phy/phy.c      |    1 +
 include/linux/phy.h        |    7 ++++
 4 files changed, 101 insertions(+), 19 deletions(-)

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[PATCH 1/2] net phy: Add mdio buses to mdio_bus_type

[Sascha Hauer]

Following the Linux example this adds both the mdio buses and the
phy devices found on the bus to the mdio_bus_type. This patch
uses the type_data field in struct device_d to distinguish between
both types.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/net/phy/mdio_bus.c |   18 ++++++++++++++++++
 drivers/net/phy/phy.c      |    1 +
 include/linux/phy.h        |    7 +++++++
 3 files changed, 26 insertions(+)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index d1d802b..173a3b2 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -47,6 +47,8 @@ int mdiobus_register(struct mii_bus *bus)
 	bus->dev.id = DEVICE_ID_DYNAMIC;
 	strcpy(bus->dev.name, "miibus");
 	bus->dev.parent = bus->parent;
+	bus->dev.bus = &mdio_bus_type;
+	bus->dev.type_data = (void *)MDIO_BUS_TYPE;
 
 	err = register_device(&bus->dev);
 	if (err) {
@@ -74,6 +76,22 @@ void mdiobus_unregister(struct mii_bus *bus)
 }
 EXPORT_SYMBOL(mdiobus_unregister);
 
+struct mii_bus *mdiobus_find(const char *name)
+{
+	struct device_d *dev;
+
+	for_each_mdiobus(dev) {
+		if (dev->type_data != (void *)MDIO_BUS_TYPE)
+			continue;
+
+		if (!strcmp(dev_name(dev), name))
+			return to_mii_bus(dev);
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(mdiobus_find);
+
 struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
 {
 	struct phy_device *phydev;
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 1cf2cb9..33ce622 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -229,6 +229,7 @@ static int phy_register_device(struct phy_device* dev)
 	int ret;
 
 	dev->dev.parent = &dev->attached_dev->dev;
+	dev->dev.type_data = (void *)MDIO_PHY_DEVICE_TYPE;
 
 	ret = register_device(&dev->dev);
 	if (ret)
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 6c9cac9..00820e8 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -87,9 +87,13 @@ struct mii_bus {
 };
 #define to_mii_bus(d) container_of(d, struct mii_bus, dev)
 
+#define for_each_mdiobus(dev) \
+	bus_for_each_device(&mdio_bus_type, dev)
+
 int mdiobus_register(struct mii_bus *bus);
 void mdiobus_unregister(struct mii_bus *bus);
 struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr);
+struct mii_bus *mdiobus_find(const char *name);
 
 /**
  * mdiobus_read - Convenience function for reading a given MII mgmt register
@@ -286,5 +290,8 @@ int phy_register_fixup_for_uid(u32 phy_uid, u32 phy_uid_mask,
 		int (*run)(struct phy_device *));
 int phy_scan_fixups(struct phy_device *phydev);
 
+#define MDIO_PHY_DEVICE_TYPE	1
+#define MDIO_BUS_TYPE		2
+
 extern struct bus_type mdio_bus_type;
 #endif /* __PHYDEV_H__ */
-- 
1.7.10.4


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[PATCH 2/2] miitool: Add support for examing mdio bus

[Sascha Hauer]

Current miitool usage is limited to a single phy on a mdio bus.

For debugging purposes it is useful to be able to examine a mdio bus
instead of a single phy only.

This adds support for this to the miitool command.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 commands/miitool.c |   94 +++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 75 insertions(+), 19 deletions(-)

diff --git a/commands/miitool.c b/commands/miitool.c
index 3a9ac45..b9e2333 100644
--- a/commands/miitool.c
+++ b/commands/miitool.c
@@ -37,23 +37,36 @@
 #include <linux/stat.h>
 #include <xfuncs.h>
 #include <linux/mii.h>
+#include <linux/phy.h>
 
-static u16 mdio_read(int fd, int offset)
+static int phy_fd;
+
+static u16 mdio_file_read(int offset)
 {
 	int ret;
 	u16 buf;
 
-	ret = lseek(fd, offset << 1, SEEK_SET);
+	ret = lseek(phy_fd, offset << 1, SEEK_SET);
 	if (ret < 0)
 		return 0;
 
-	ret = read(fd, &buf, sizeof(u16));
+	ret = read(phy_fd, &buf, sizeof(u16));
 	if (ret < 0)
 		return 0;
 
 	return buf;
 }
 
+static struct mii_bus *mii_bus;
+static int mii_address;
+
+static u16 mdio_bus_read(int offset)
+{
+	return mdiobus_read(mii_bus, mii_address, offset);
+}
+
+static u16 (*mdio_read)(int offset);
+
 /* Table of known MII's */
 static const struct {
 	u_short	id1, id2;
@@ -101,7 +114,7 @@ static char *media_list(int mask, int best)
 	return buf;
 }
 
-static int show_basic_mii(int fd, int verbose)
+static int show_basic_mii(int verbose)
 {
 	char buf[100];
 	int i, mii_val[32];
@@ -109,9 +122,9 @@ static int show_basic_mii(int fd, int verbose)
 
 	/* Some bits in the BMSR are latched, but we can't rely on being
 	   the only reader, so only the current values are meaningful */
-	mdio_read(fd, MII_BMSR);
+	mdio_read(MII_BMSR);
 	for (i = 0; i < ((verbose > 1) ? 32 : 8); i++)
-		mii_val[i] = mdio_read(fd, i);
+		mii_val[i] = mdio_read(i);
 
 	if (mii_val[MII_BMCR] == 0xffff) {
 		fprintf(stderr, "  No MII transceiver present!.\n");
@@ -213,18 +226,25 @@ static int show_basic_mii(int fd, int verbose)
 
 static int do_miitool(int argc, char *argv[])
 {
-	char *filename;
+	char *filename = NULL;
+	char *devname = NULL;
 	int opt;
 	int argc_min;
-	int fd;
 	int verbose;
+	int address = -1;
 
 	verbose = 0;
-	while ((opt = getopt(argc, argv, "v")) > 0) {
+	while ((opt = getopt(argc, argv, "vd:a:")) > 0) {
 		switch (opt) {
 		case 'v':
 			verbose++;
 			break;
+		case 'd':
+			devname = optarg;
+			break;
+		case 'a':
+			address = simple_strtoul(optarg, NULL, 0);
+			break;
 		default:
 			return COMMAND_ERROR_USAGE;
 		}
@@ -232,27 +252,63 @@ static int do_miitool(int argc, char *argv[])
 
 	argc_min = optind + 1;
 
-	if (argc < argc_min)
+	if (argc >= argc_min)
+		filename = argv[optind];
+
+	if (filename && devname) {
+		printf("both filename and devicename given\n");
 		return COMMAND_ERROR_USAGE;
+	}
 
-	filename = argv[optind];
+	if (!filename && !devname) {
+		printf("no filename or devicename given\n");
+		return COMMAND_ERROR_USAGE;
+	}
+
+	if (filename) {
+		phy_fd = open(filename, O_RDONLY);
+		if (phy_fd < 0) {
+			printf("unable to read %s\n", filename);
+			return COMMAND_ERROR;
+		}
+
+		mdio_read = mdio_file_read;
+
+		show_basic_mii(verbose);
+	} else {
+		mii_bus = mdiobus_find(devname);
+
+		if (!mii_bus)
+			return -ENODEV;
 
-	fd = open(filename, O_RDONLY);
-	if (fd < 0) {
-		printf("unable to read %s\n", filename);
-		return COMMAND_ERROR;
+		mdio_read = mdio_bus_read;
+		if (address < 0) {
+			for (mii_address = 0; mii_address < PHY_MAX_ADDR; mii_address++) {
+				printf("`---- phyadr %d:\n",
+						mii_address);
+				show_basic_mii(verbose);
+			}
+		} else {
+			mii_address = address;
+			show_basic_mii(verbose);
+		}
 	}
 
-	show_basic_mii(fd, verbose);
 
-	close(fd);
+	if (filename)
+		close(phy_fd);
 
 	return COMMAND_SUCCESS;
 }
 
 BAREBOX_CMD_HELP_START(miitool)
-BAREBOX_CMD_HELP_USAGE("miitool [[[-v] -v] -v] <phy>\n")
-BAREBOX_CMD_HELP_SHORT("view status for MII <phy>.\n")
+BAREBOX_CMD_HELP_USAGE("miitool [OPTIONS] [phy]\n")
+BAREBOX_CMD_HELP_SHORT("view status mii phy device status\n")
+BAREBOX_CMD_HELP_SHORT("Use [phy] to view a phy connected to an ethernet device\n")
+BAREBOX_CMD_HELP_SHORT("or -d <devname> [-a <phyadr>] to examine a mii bus\n")
+BAREBOX_CMD_HELP_OPT("-v", "\tverbose, may be given multiple times\n")
+BAREBOX_CMD_HELP_OPT("-d <devname>", "work on miibus <devname>\n")
+BAREBOX_CMD_HELP_OPT("-a <phyadr>", "Use phy address <phyadr>, used together with -d\n")
 BAREBOX_CMD_HELP_END
 
 /**
-- 
1.7.10.4


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Re: [PATCH 2/2] miitool: Add support for examing mdio bus

[Alexander Aring]

Hi Sascha,

On Fri, Feb 08, 2013 at 10:24:17AM +0100, Sascha Hauer wrote:
> Current miitool usage is limited to a single phy on a mdio bus.
> 
> For debugging purposes it is useful to be able to examine a mdio bus
> instead of a single phy only.
> 
> This adds support for this to the miitool command.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  commands/miitool.c |   94 +++++++++++++++++++++++++++++++++++++++++-----------
>  1 file changed, 75 insertions(+), 19 deletions(-)
> 
> diff --git a/commands/miitool.c b/commands/miitool.c
> index 3a9ac45..b9e2333 100644
> --- a/commands/miitool.c
> +++ b/commands/miitool.c
> @@ -37,23 +37,36 @@
>  #include <linux/stat.h>
>  #include <xfuncs.h>
>  #include <linux/mii.h>
> +#include <linux/phy.h>
>  
> -static u16 mdio_read(int fd, int offset)
> +static int phy_fd;
> +
> +static u16 mdio_file_read(int offset)
>  {
>  	int ret;
>  	u16 buf;
>  
> -	ret = lseek(fd, offset << 1, SEEK_SET);
> +	ret = lseek(phy_fd, offset << 1, SEEK_SET);
>  	if (ret < 0)
>  		return 0;
>  
> -	ret = read(fd, &buf, sizeof(u16));
> +	ret = read(phy_fd, &buf, sizeof(u16));
>  	if (ret < 0)
>  		return 0;
>  
>  	return buf;
>  }

I made a similar function in nandtest and I am thinking about to add a
pread and pwrite into file operations.
Is it welcome to send patches for adding pwrite and pread into file
operations? I would implement it like this but with a prototype
which looks like:

ssize_t pread(int fildes, void *buf, size_t nbyte, off_t offset);


Another thing:
You drop the errno in this function. I don't know about the driver bus
implementation if it can return -EIO or -EBUSY. I know it's not easy to
handle it because you return the buffer. But we can change the function
like this:

static int mdio_file_read(int offset, u16 *buf); to handle error.

It's only a small thing that I detected.

>  
> +static struct mii_bus *mii_bus;
> +static int mii_address;
> +
> +static u16 mdio_bus_read(int offset)
> +{
> +	return mdiobus_read(mii_bus, mii_address, offset);
> +}
> +

This would be:
static int mdio_bus_read(int offset, u16 *buf);
But it seems that this function will drop no errno.

> +static u16 (*mdio_read)(int offset);

static int (*mdio_read)(int offset, u16 *buf);

> +
>  /* Table of known MII's */
>  static const struct {
>  	u_short	id1, id2;
> @@ -101,7 +114,7 @@ static char *media_list(int mask, int best)
>  	return buf;
>  }
>  
> -static int show_basic_mii(int fd, int verbose)
> +static int show_basic_mii(int verbose)
>  {
>  	char buf[100];
>  	int i, mii_val[32];

In current implementation mii_val can be a u16 array.

> @@ -109,9 +122,9 @@ static int show_basic_mii(int fd, int verbose)
>  
>  	/* Some bits in the BMSR are latched, but we can't rely on being
>  	   the only reader, so only the current values are meaningful */
> -	mdio_read(fd, MII_BMSR);
> +	mdio_read(MII_BMSR);

Then we can handle it here.

>  	for (i = 0; i < ((verbose > 1) ? 32 : 8); i++)
> -		mii_val[i] = mdio_read(fd, i);
> +		mii_val[i] = mdio_read(i);
>  
>  	if (mii_val[MII_BMCR] == 0xffff) {
>  		fprintf(stderr, "  No MII transceiver present!.\n");
> @@ -213,18 +226,25 @@ static int show_basic_mii(int fd, int verbose)
>  
>  static int do_miitool(int argc, char *argv[])
>  {
> -	char *filename;
> +	char *filename = NULL;
> +	char *devname = NULL;
>  	int opt;
>  	int argc_min;
> -	int fd;
>  	int verbose;
> +	int address = -1;
>  
>  	verbose = 0;
> -	while ((opt = getopt(argc, argv, "v")) > 0) {
> +	while ((opt = getopt(argc, argv, "vd:a:")) > 0) {
>  		switch (opt) {
>  		case 'v':
>  			verbose++;
>  			break;
> +		case 'd':
> +			devname = optarg;
> +			break;
> +		case 'a':
> +			address = simple_strtoul(optarg, NULL, 0);
> +			break;
>  		default:
>  			return COMMAND_ERROR_USAGE;
>  		}
> @@ -232,27 +252,63 @@ static int do_miitool(int argc, char *argv[])
>  
>  	argc_min = optind + 1;
>  
> -	if (argc < argc_min)
> +	if (argc >= argc_min)
> +		filename = argv[optind];
> +
> +	if (filename && devname) {
> +		printf("both filename and devicename given\n");
>  		return COMMAND_ERROR_USAGE;
> +	}
>  
> -	filename = argv[optind];
> +	if (!filename && !devname) {
> +		printf("no filename or devicename given\n");
> +		return COMMAND_ERROR_USAGE;
> +	}
> +
> +	if (filename) {
> +		phy_fd = open(filename, O_RDONLY);
> +		if (phy_fd < 0) {
> +			printf("unable to read %s\n", filename);
> +			return COMMAND_ERROR;
> +		}
> +
> +		mdio_read = mdio_file_read;
> +
> +		show_basic_mii(verbose);

If we handle error, don't forget to close phy_fd here.

Regards
Alex

> +	} else {
> +		mii_bus = mdiobus_find(devname);
> +
> +		if (!mii_bus)
> +			return -ENODEV;
>  
> -	fd = open(filename, O_RDONLY);
> -	if (fd < 0) {
> -		printf("unable to read %s\n", filename);
> -		return COMMAND_ERROR;
> +		mdio_read = mdio_bus_read;
> +		if (address < 0) {
> +			for (mii_address = 0; mii_address < PHY_MAX_ADDR; mii_address++) {
> +				printf("`---- phyadr %d:\n",
> +						mii_address);
> +				show_basic_mii(verbose);
> +			}
> +		} else {
> +			mii_address = address;
> +			show_basic_mii(verbose);
> +		}
>  	}
>  
> -	show_basic_mii(fd, verbose);
>  
> -	close(fd);
> +	if (filename)
> +		close(phy_fd);
>  
>  	return COMMAND_SUCCESS;
>  }
>  
>  BAREBOX_CMD_HELP_START(miitool)
> -BAREBOX_CMD_HELP_USAGE("miitool [[[-v] -v] -v] <phy>\n")
> -BAREBOX_CMD_HELP_SHORT("view status for MII <phy>.\n")
> +BAREBOX_CMD_HELP_USAGE("miitool [OPTIONS] [phy]\n")
> +BAREBOX_CMD_HELP_SHORT("view status mii phy device status\n")
> +BAREBOX_CMD_HELP_SHORT("Use [phy] to view a phy connected to an ethernet device\n")
> +BAREBOX_CMD_HELP_SHORT("or -d <devname> [-a <phyadr>] to examine a mii bus\n")
> +BAREBOX_CMD_HELP_OPT("-v", "\tverbose, may be given multiple times\n")
> +BAREBOX_CMD_HELP_OPT("-d <devname>", "work on miibus <devname>\n")
> +BAREBOX_CMD_HELP_OPT("-a <phyadr>", "Use phy address <phyadr>, used together with -d\n")
>  BAREBOX_CMD_HELP_END
>  
>  /**
> -- 
> 1.7.10.4
> 
> 
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> barebox@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/barebox

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Re: [PATCH 2/2] miitool: Add support for examing mdio bus

[Sascha Hauer]

On Fri, Feb 08, 2013 at 12:02:20PM +0100, Alexander Aring wrote:
> Hi Sascha,
> 
> On Fri, Feb 08, 2013 at 10:24:17AM +0100, Sascha Hauer wrote:
> > Current miitool usage is limited to a single phy on a mdio bus.
> > 
> > For debugging purposes it is useful to be able to examine a mdio bus
> > instead of a single phy only.
> > 
> > This adds support for this to the miitool command.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > ---
> >  commands/miitool.c |   94 +++++++++++++++++++++++++++++++++++++++++-----------
> >  1 file changed, 75 insertions(+), 19 deletions(-)
> > 
> > diff --git a/commands/miitool.c b/commands/miitool.c
> > index 3a9ac45..b9e2333 100644
> > --- a/commands/miitool.c
> > +++ b/commands/miitool.c
> > @@ -37,23 +37,36 @@
> >  #include <linux/stat.h>
> >  #include <xfuncs.h>
> >  #include <linux/mii.h>
> > +#include <linux/phy.h>
> >  
> > -static u16 mdio_read(int fd, int offset)
> > +static int phy_fd;
> > +
> > +static u16 mdio_file_read(int offset)
> >  {
> >  	int ret;
> >  	u16 buf;
> >  
> > -	ret = lseek(fd, offset << 1, SEEK_SET);
> > +	ret = lseek(phy_fd, offset << 1, SEEK_SET);
> >  	if (ret < 0)
> >  		return 0;
> >  
> > -	ret = read(fd, &buf, sizeof(u16));
> > +	ret = read(phy_fd, &buf, sizeof(u16));
> >  	if (ret < 0)
> >  		return 0;
> >  
> >  	return buf;
> >  }
> 
> I made a similar function in nandtest and I am thinking about to add a
> pread and pwrite into file operations.
> Is it welcome to send patches for adding pwrite and pread into file
> operations? I would implement it like this but with a prototype
> which looks like:
> 
> ssize_t pread(int fildes, void *buf, size_t nbyte, off_t offset);

Sounds good. Just to be sure: With 'file operations' you do not mean
struct file_operations, right?

> 
> 
> Another thing:
> You drop the errno in this function. I don't know about the driver bus
> implementation if it can return -EIO or -EBUSY. I know it's not easy to
> handle it because you return the buffer. But we can change the function
> like this:
> 
> static int mdio_file_read(int offset, u16 *buf); to handle error.
> 
> It's only a small thing that I detected.

Ok, can fix this.

Sascha

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Re: [PATCH 2/2] miitool: Add support for examing mdio bus

[Alexander Aring]

Hi Sascha,

On Mon, Feb 11, 2013 at 12:40:23PM +0100, Sascha Hauer wrote:
> On Fri, Feb 08, 2013 at 12:02:20PM +0100, Alexander Aring wrote:
> > Hi Sascha,
> > 
> > On Fri, Feb 08, 2013 at 10:24:17AM +0100, Sascha Hauer wrote:
> > > Current miitool usage is limited to a single phy on a mdio bus.
> > > 
> > > For debugging purposes it is useful to be able to examine a mdio bus
> > > instead of a single phy only.
> > > 
> > > This adds support for this to the miitool command.
> > > 
> > > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > > ---
> > >  commands/miitool.c |   94 +++++++++++++++++++++++++++++++++++++++++-----------
> > >  1 file changed, 75 insertions(+), 19 deletions(-)
> > > 
> > > diff --git a/commands/miitool.c b/commands/miitool.c
> > > index 3a9ac45..b9e2333 100644
> > > --- a/commands/miitool.c
> > > +++ b/commands/miitool.c
> > > @@ -37,23 +37,36 @@
> > >  #include <linux/stat.h>
> > >  #include <xfuncs.h>
> > >  #include <linux/mii.h>
> > > +#include <linux/phy.h>
> > >  
> > > -static u16 mdio_read(int fd, int offset)
> > > +static int phy_fd;
> > > +
> > > +static u16 mdio_file_read(int offset)
> > >  {
> > >  	int ret;
> > >  	u16 buf;
> > >  
> > > -	ret = lseek(fd, offset << 1, SEEK_SET);
> > > +	ret = lseek(phy_fd, offset << 1, SEEK_SET);
> > >  	if (ret < 0)
> > >  		return 0;
> > >  
> > > -	ret = read(fd, &buf, sizeof(u16));
> > > +	ret = read(phy_fd, &buf, sizeof(u16));
> > >  	if (ret < 0)
> > >  		return 0;
> > >  
> > >  	return buf;
> > >  }
> > 
> > I made a similar function in nandtest and I am thinking about to add a
> > pread and pwrite into file operations.
> > Is it welcome to send patches for adding pwrite and pread into file
> > operations? I would implement it like this but with a prototype
> > which looks like:
> > 
> > ssize_t pread(int fildes, void *buf, size_t nbyte, off_t offset);
> 
> Sounds good. Just to be sure: With 'file operations' you do not mean
> struct file_operations, right?
> 

I can do this in two ways.

Option 1:

Write 'file_operations helper functions' for pwrite and pread. Each driver can
assign this to pwrite and pread callbacks in file_operations struct.

Similar we can do that for a normal file fs_driver_d.

This helper functions just call lseek and write or read for specific
device/filesystem.
If callback is null, driver or filesystem doesn't support it.

pread and pwrite implementation in fs/fs.c will call assign callback
from fs_driver_d.

Option 2:

Just add a pwrite and pread function in fs/fs.c which calls for a
filedescriptor lseek and then write or read.

---

I prefer option 2. This implementation used smaller size and it works
like option 1. It's just a call of read or write with an specific offset.

But in option 1 a driver or filesystem can replace this function with an
another function which can do something other than just call lseek and then
write or read.

Regards
Alex

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Re: [PATCH 2/2] miitool: Add support for examing mdio bus

[Sascha Hauer]

On Tue, Feb 12, 2013 at 12:13:06AM +0100, Alexander Aring wrote:
> Hi Sascha,
> 
> On Mon, Feb 11, 2013 at 12:40:23PM +0100, Sascha Hauer wrote:
> > On Fri, Feb 08, 2013 at 12:02:20PM +0100, Alexander Aring wrote:
> > > Hi Sascha,
> > > 
> > > On Fri, Feb 08, 2013 at 10:24:17AM +0100, Sascha Hauer wrote:
> > > > Current miitool usage is limited to a single phy on a mdio bus.
> > > > 
> > > > For debugging purposes it is useful to be able to examine a mdio bus
> > > > instead of a single phy only.
> > > > 
> > > > This adds support for this to the miitool command.
> > > > 
> > > > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > > > ---
> > > >  commands/miitool.c |   94 +++++++++++++++++++++++++++++++++++++++++-----------
> > > >  1 file changed, 75 insertions(+), 19 deletions(-)
> > > > 
> > > > diff --git a/commands/miitool.c b/commands/miitool.c
> > > > index 3a9ac45..b9e2333 100644
> > > > --- a/commands/miitool.c
> > > > +++ b/commands/miitool.c
> > > > @@ -37,23 +37,36 @@
> > > >  #include <linux/stat.h>
> > > >  #include <xfuncs.h>
> > > >  #include <linux/mii.h>
> > > > +#include <linux/phy.h>
> > > >  
> > > > -static u16 mdio_read(int fd, int offset)
> > > > +static int phy_fd;
> > > > +
> > > > +static u16 mdio_file_read(int offset)
> > > >  {
> > > >  	int ret;
> > > >  	u16 buf;
> > > >  
> > > > -	ret = lseek(fd, offset << 1, SEEK_SET);
> > > > +	ret = lseek(phy_fd, offset << 1, SEEK_SET);
> > > >  	if (ret < 0)
> > > >  		return 0;
> > > >  
> > > > -	ret = read(fd, &buf, sizeof(u16));
> > > > +	ret = read(phy_fd, &buf, sizeof(u16));
> > > >  	if (ret < 0)
> > > >  		return 0;
> > > >  
> > > >  	return buf;
> > > >  }
> > > 
> > > I made a similar function in nandtest and I am thinking about to add a
> > > pread and pwrite into file operations.
> > > Is it welcome to send patches for adding pwrite and pread into file
> > > operations? I would implement it like this but with a prototype
> > > which looks like:
> > > 
> > > ssize_t pread(int fildes, void *buf, size_t nbyte, off_t offset);
> > 
> > Sounds good. Just to be sure: With 'file operations' you do not mean
> > struct file_operations, right?
> > 
> 
> I can do this in two ways.
> 
> Option 1:
> 
> Write 'file_operations helper functions' for pwrite and pread. Each driver can
> assign this to pwrite and pread callbacks in file_operations struct.
> 
> Similar we can do that for a normal file fs_driver_d.
> 
> This helper functions just call lseek and write or read for specific
> device/filesystem.
> If callback is null, driver or filesystem doesn't support it.
> 
> pread and pwrite implementation in fs/fs.c will call assign callback
> from fs_driver_d.
> 
> Option 2:
> 
> Just add a pwrite and pread function in fs/fs.c which calls for a
> filedescriptor lseek and then write or read.
> 
> ---
> 
> I prefer option 2. This implementation used smaller size and it works
> like option 1. It's just a call of read or write with an specific offset.
> 
> But in option 1 a driver or filesystem can replace this function with an
> another function which can do something other than just call lseek and then
> write or read.

I also vote for option 2; option 1 could be implemented should the need
arise, but I currently don't see it.

Sascha

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