[PATCH v3] mfd: syscon: Decouple syscon interface from platform devices
Li.Xiubo at freescale.com
Li.Xiubo at freescale.com
Thu Sep 18 20:38:03 PDT 2014
> > Thanks for testing. In that case I will post this change, as I feel this
> > should be
> > fixed irrespective of my syscon patch.
> >
> > > But as Xiubo pointed in another mail, it may still cause other issues.
> > > Looking at regmap.c, there're still some other places using the device
> > pointer, e.g.
> > > dev_xxx debug information and some tracepoints also take device pointer as
> > > parameter(not sure if it will break if dev is NULL).
> > > Another thing is that if dev is NULL, we may not be able to use regmap
> > debugfs
> > > feature which seems also not as our expected.
> > >
> >
> > I would have preferred to check dev for NULL, as it's only at two places and
> > we could
> > still have debug prints for NULL dev, as normal pr_info instead of dev_info.
> >
> > But Xiubo also pointed out that his patch [1] which updates syscon binding
> > information
> > will be useless if we pass NULL dev in regmap_init_mmio, which he posted
> > today,
> > and it requires dev pointer in "regmap_get_val_endian" function to read DT
> > property.
> >
> > [1]: [PATCH] mfd: syscon: binding: Add syscon endianness support
> > https://lkml.org/lkml/2014/9/18/67
> >
> > So instead of adding dummy device or creating device structure, I would
> > prefer to get actual
> > device pointer corresponding to "np" passed in of_syscon_register function
> > as shown below:
> >
>
> I wonder this may not work at early stage before the devices are populated
> from device tree.
> My initial understanding that one important thing for your patch is
> to address this issue, isn't it?
> Many people have asked for this feature before.
>
My boot log:
...
of_platform_bus_create() - skipping /chosen, no compatible prop
of_platform_bus_create() - skipping /aliases, no compatible prop
of_platform_bus_create() - skipping /memory, no compatible prop
of_platform_bus_create() - skipping /cpus, no compatible prop
create child: /soc/smmu at 1200000
create child: /soc/smmu at 1280000
create child: /soc/smmu at 1300000
create child: /soc/smmu at 1380000
create child: /soc/interrupt-controller at 1400000
create child: /soc/tzasc at 1500000
of_platform_bus_create() - skipping /soc/tzasc at 1500000, no compatible prop
create child: /soc/ifc at 1530000
create child: /soc/ifc at 1530000/nor at 0,0
create child: /soc/ifc at 1530000/board-control at 2,0
create child: /soc/dcfg at 1ee0000
syscon 1ee0000.dcfg: regmap [mem 0x01ee0000-0x01eeffff] registered
create child: /soc/quadspi at 1550000
create child: /soc/esdhc at 1560000
create child: /soc/scfg at 1570000
create child: /soc/crypto at 1700000
create child: /soc/sfp at 1e80000
of_platform_bus_create() - skipping /soc/sfp at 1e80000, no compatible prop
create child: /soc/snvs at 1e90000
of_platform_bus_create() - skipping /soc/snvs at 1e90000, no compatible prop
create child: /soc/serdes1 at 1ea0000
of_platform_bus_create() - skipping /soc/serdes1 at 1ea0000, no compatible prop
create child: /soc/clocking at 1ee1000
create child: /soc/rcpm at 1ee2000
create child: /soc/dspi at 2100000
create child: /soc/dspi at 2110000
create child: /soc/i2c at 2180000
create child: /soc/i2c at 2190000
create child: /soc/i2c at 21a0000
create child: /soc/serial at 21c0500
create child: /soc/serial at 21c0600
create child: /soc/serial at 21d0500
create child: /soc/serial at 21d0600
create child: /soc/gpio at 2300000
create child: /soc/gpio at 2310000
create child: /soc/gpio at 2320000
create child: /soc/gpio at 2330000
create child: /soc/uqe at 2400000
create child: /soc/uqe at 2400000/qeic at 80
create child: /soc/uqe at 2400000/ucc at 2000
irq: no irq domain found for /soc/uqe at 2400000/qeic at 80 !
create child: /soc/uqe at 2400000/ucc at 2200
irq: no irq domain found for /soc/uqe at 2400000/qeic at 80 !
create child: /soc/uqe at 2400000/muram at 10000
create child: /soc/uqe at 2400000/si at 700
create child: /soc/uqe at 2400000/siram at 1000
create child: /soc/serial at 2950000
create child: /soc/serial at 2960000
create child: /soc/serial at 2970000
create child: /soc/serial at 2980000
create child: /soc/serial at 2990000
create child: /soc/serial at 29a0000
create child: /soc/ftm0_1 at 29d0000
create child: /soc/ftm at 29f0000
of_platform_bus_create() - skipping /soc/ftm at 29f0000, no compatible prop
create child: /soc/ftm at 2a00000
create child: /soc/ftm at 2a10000
of_platform_bus_create() - skipping /soc/ftm at 2a10000, no compatible prop
create child: /soc/ftm at 2a20000
of_platform_bus_create() - skipping /soc/ftm at 2a20000, no compatible prop
create child: /soc/ftm at 2a30000
create child: /soc/ftm at 2a40000
create child: /soc/wdog at 2ad0000
create child: /soc/sai at 2b60000
create child: /soc/edma at 2c00000
create child: /soc/dcu at 2ce0000
create child: /soc/mdio at 2d24000
create child: /soc/ptp_clock at 2d10e00
create child: /soc/ethernet at 2d10000
create child: /soc/ethernet at 2d50000
create child: /soc/ethernet at 2d90000
create child: /soc/usb at 8600000
create child: /soc/usb3 at 3100000
create child: /soc/can at 2a70000
create child: /soc/can at 2a80000
create child: /soc/can at 2a90000
create child: /soc/can at 2aa0000
create child: /soc/pcie at 3400000
create child: /soc/pcie at 3500000
create child: /dcsr at 20000000/dcsr-epu at 0
create child: /dcsr at 20000000/dcsr-gdi at 100000
create child: /dcsr at 20000000/dcsr-dddi at 120000
create child: /dcsr at 20000000/dcsr-dcfg at 220000
create child: /dcsr at 20000000/dcsr-clock at 221000
create child: /dcsr at 20000000/dcsr-rcpm at 222000
create child: /dcsr at 20000000/dcsr-ccp at 225000
create child: /dcsr at 20000000/dcsr-fusectrl at 226000
create child: /dcsr at 20000000/dcsr-dap at 300000
create child: /dcsr at 20000000/dcsr-cstf at 350000
create child: /dcsr at 20000000/dcsr-a7rom at 360000
create child: /dcsr at 20000000/dcsr-a7cpu at 370000
create child: /dcsr at 20000000/dcsr-a7cti at 378000
create child: /dcsr at 20000000/dcsr-etm at 37c000
create child: /dcsr at 20000000/dcsr-hugorom at 3a0000
create child: /dcsr at 20000000/dcsr-etf at 3a1000
create child: /dcsr at 20000000/dcsr-etr at 3a3000
create child: /dcsr at 20000000/dcsr-cti at 3a4000
create child: /dcsr at 20000000/dcsr-atbrepl at 3a8000
create child: /dcsr at 20000000/dcsr-tsgen-ctrl at 3a9000
create child: /dcsr at 20000000/dcsr-tsgen-read at 3aa000
create child: /regulators/regulator at 0
...
As default the Linux will create all the platform device for each DT node, which
Can be found from "drivers/of/platform.c".
So we can get the pdev node using the specified DT node, and feel safe to use
it as Pankaj's patch does.
And also we must make sure that the 'syscon' DT nodes has the compatible prop.
Thanks,
BRs
Xiubo
> Regards
> Dong Aisheng
>
> > ----
> > static struct syscon *of_syscon_register(struct device_node *np)
> > {
> > + struct platform_device *pdev;
> > struct syscon *syscon;
> > struct regmap *regmap;
> > void __iomem *base;
> > @@ -142,7 +144,11 @@ static struct syscon *of_syscon_register(struct
> > device_node *np)
> > if (!base)
> > return ERR_PTR(-ENOMEM);
> >
> > - regmap = regmap_init_mmio(NULL, base, &syscon_regmap_config);
> > + pdev = of_find_device_by_node(np);
> > + if (!(&pdev->dev))
> > + return ERR_PTR(-ENODEV);
> > +
> > + regmap = regmap_init_mmio(&pdev->dev, base, &syscon_regmap_config);
> > if (IS_ERR(regmap)) {
> > pr_err("regmap init failed\n");
> > return ERR_CAST(regmap);
> > -------
> >
> > I have tested this in linux-next and it works well. In this way there won't
> > be any issues of
> > dereferencing NULL pointer in regmap.c and at the same time, if DT has
> > {big,little}-endian
> > optional property in syscon device node, it will be taken care.
> >
> > So I would wait for Arnd's opinion about above mentioned changes and then
> > post a new
> > change after addressing Arnd's minor comment along with this fix in next
> > revision.
> >
> >
> > Thanks,
> > Pankaj Dubey
> > > Maybe we could consider create device structure for each syscon compatible
> > device in
> > > syscon driver in of_syscon_register in first time which seems to be
> > reasonable.
> > >
> > > Regards
> > > Dong Aisheng
> > >
> > > > --------------------------------------------
> > > > Subject: [PATCH] regmap: fix NULL pointer dereference in
> > > > regmap_get_val_endian
> > > >
> > > > Recent commits for getting reg endianess causing NULL pointer
> > > > dereference if dev is passed NULL in regmap_init_mmio. This patch
> > > > fixes this issue, and allows to parse reg endianess only if dev and
> > > > dev->of_node exist.
> > > >
> > > > Signed-off-by: Pankaj Dubey <pankaj.dubey at samsung.com>
> > > > ---
> > > > drivers/base/regmap/regmap.c | 23 ++++++++++++++---------
> > > > 1 file changed, 14 insertions(+), 9 deletions(-)
> > > >
> > > > diff --git a/drivers/base/regmap/regmap.c
> > > > b/drivers/base/regmap/regmap.c index f2281af..455a877 100644
> > > > --- a/drivers/base/regmap/regmap.c
> > > > +++ b/drivers/base/regmap/regmap.c
> > > > @@ -477,7 +477,7 @@ static enum regmap_endian
> > > > regmap_get_val_endian(struct device *dev,
> > > > const struct regmap_bus *bus,
> > > > const struct regmap_config *config)
> > {
> > > > - struct device_node *np = dev->of_node;
> > > > + struct device_node *np;
> > > > enum regmap_endian endian;
> > > >
> > > > /* Retrieve the endianness specification from the regmap config
> */
> > > > @@ -487,15 +487,20 @@ static enum regmap_endian
> > > > regmap_get_val_endian(struct device *dev,
> > > > if (endian != REGMAP_ENDIAN_DEFAULT)
> > > > return endian;
> > > >
> > > > - /* Parse the device's DT node for an endianness specification */
> > > > - if (of_property_read_bool(np, "big-endian"))
> > > > - endian = REGMAP_ENDIAN_BIG;
> > > > - else if (of_property_read_bool(np, "little-endian"))
> > > > - endian = REGMAP_ENDIAN_LITTLE;
> > > > + /* If the dev and dev->of_node exist try to get endianness from
> DT
> > > > */
> > > > + if (dev && dev->of_node) {
> > > > + np = dev->of_node;
> > > >
> > > > - /* If the endianness was specified in DT, use that */
> > > > - if (endian != REGMAP_ENDIAN_DEFAULT)
> > > > - return endian;
> > > > + /* Parse the device's DT node for an endianness
> > > > specification */
> > > > + if (of_property_read_bool(np, "big-endian"))
> > > > + endian = REGMAP_ENDIAN_BIG;
> > > > + else if (of_property_read_bool(np, "little-endian"))
> > > > + endian = REGMAP_ENDIAN_LITTLE;
> > > > +
> > > > + /* If the endianness was specified in DT, use that */
> > > > + if (endian != REGMAP_ENDIAN_DEFAULT)
> > > > + return endian;
> > > > + }
> > > >
> > > > /* Retrieve the endianness specification from the bus config */
> > > > if (bus && bus->val_format_endian_default)
> > > > --
> > > >
> > > > Thanks,
> > > > Pankaj Dubey
> > > >
> > > > > Regards
> > > > > Dong Aisheng
> > > > >
> > > > > >
> > > > > > Thanks,
> > > > > > Pankaj Dubey
> > > > > >
> > > > > > > Regards
> > > > > > > Dong Aisheng
> > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > _______________________________________________
> > > > > > > > linux-arm-kernel mailing list
> > > > > > > > linux-arm-kernel at lists.infradead.org
> > > > > > > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> > > > > >
> > > >
> >
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