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Message-ID: <20150121125623.GB22024@x1>
Date: Wed, 21 Jan 2015 12:56:23 +0000
From: Lee Jones <lee.jones@...aro.org>
To: Brian Norris <computersforpeace@...il.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-mtd@...ts.infradead.org, kernel@...inux.com,
devicetree@...r.kernel.org
Subject: Re: [PATCH v3 04/13] mtd: st_spi_fsm: Fetch boot device locations
from DT match tables
On Mon, 12 Jan 2015, Brian Norris wrote:
> + devicetree
>
> On Mon, Dec 15, 2014 at 11:59:11AM +0000, Lee Jones wrote:
> > To trim down on the amount of properties used by this driver and to conform
> > to the newly agreed method of acquiring syscfg registers/offsets, we now
> > obtain this information using match tables.
> >
> > In the process we are deprecating the old generic compatible string and
> > providing 3 shiny new ones for each of the support platforms. The
> > deprecated compatible string will be removed in due course.
>
> I'm not sure how this agreement was done, but by default, we expect not
> to break backwards compatibility. This patch does just that.
>
> > Signed-off-by: Lee Jones <lee.jones@...aro.org>
> > ---
> > drivers/mtd/devices/st_spi_fsm.c | 75 ++++++++++++++++++++++++++++++----------
> > 1 file changed, 57 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/mtd/devices/st_spi_fsm.c b/drivers/mtd/devices/st_spi_fsm.c
> > index fac0fe9..d82394a 100644
> > --- a/drivers/mtd/devices/st_spi_fsm.c
> > +++ b/drivers/mtd/devices/st_spi_fsm.c
> > @@ -29,6 +29,21 @@
> > #include "serial_flash_cmds.h"
> >
> > /*
> > + * FSM SPI Boot Mode Registers/Masks
> > + */
> > +#define STID127_SYSCON_BOOT_DEV_REG 0x0D8
> > +#define STID127_SYSCON_BOOT_DEV_SPI 0x068
> > +#define STID127_SYSCON_BOOT_DEV_MASK 0x07C
> > +
> > +#define STIH407_SYSCON_BOOT_DEV_REG 0x8C4
> > +#define STIH407_SYSCON_BOOT_DEV_SPI 0x068
> > +#define STIH407_SYSCON_BOOT_DEV_MASK 0x07C
> > +
> > +#define STIH416_SYSCON_BOOT_DEV_REG 0x958
> > +#define STIH416_SYSCON_BOOT_DEV_SPI 0x01A
> > +#define STIH416_SYSCON_BOOT_DEV_MASK 0x01F
> > +
> > +/*
> > * FSM SPI Controller Registers
> > */
> > #define SPI_CLOCKDIV 0x0010
> > @@ -288,6 +303,12 @@ struct seq_rw_config {
> > uint8_t dummy_cycles; /* No. of DUMMY cycles */
> > };
> >
> > +struct stfsm_boot_dev {
> > + uint32_t reg;
> > + uint32_t spi;
> > + uint32_t mask;
> > +};
> > +
> > /* SPI Flash Device Table */
> > struct flash_info {
> > char *name;
> > @@ -313,6 +334,24 @@ struct flash_info {
> > int (*config)(struct stfsm *);
> > };
> >
> > +static struct stfsm_boot_dev stfsm_stid127_data = {
> > + .reg = STID127_SYSCON_BOOT_DEV_REG,
> > + .spi = STID127_SYSCON_BOOT_DEV_SPI,
> > + .mask = STID127_SYSCON_BOOT_DEV_MASK,
> > +};
> > +
> > +static struct stfsm_boot_dev stfsm_stih407_data = {
> > + .reg = STIH407_SYSCON_BOOT_DEV_REG,
> > + .spi = STIH407_SYSCON_BOOT_DEV_SPI,
> > + .mask = STIH407_SYSCON_BOOT_DEV_MASK,
> > +};
> > +
> > +static struct stfsm_boot_dev stfsm_stih416_data = {
> > + .reg = STIH416_SYSCON_BOOT_DEV_REG,
> > + .spi = STIH416_SYSCON_BOOT_DEV_SPI,
> > + .mask = STIH416_SYSCON_BOOT_DEV_MASK,
> > +};
> > +
> > static int stfsm_n25q_config(struct stfsm *fsm);
> > static int stfsm_mx25_config(struct stfsm *fsm);
> > static int stfsm_s25fl_config(struct stfsm *fsm);
> > @@ -1977,14 +2016,23 @@ static int stfsm_init(struct stfsm *fsm)
> > return 0;
> > }
> >
> > +static const struct of_device_id stfsm_match[] = {
> > + { .compatible = "st,spi-fsm" }, /* DEPRECATED */
> > + { .compatible = "st,stid127-spi-fsm", .data = &stfsm_stid127_data },
> > + { .compatible = "st,stih407-spi-fsm", .data = &stfsm_stih407_data },
> > + { .compatible = "st,stih416-spi-fsm", .data = &stfsm_stih416_data },
> > + {},
> > +};
> > +MODULE_DEVICE_TABLE(of, stfsm_match);
> > +
> > static void stfsm_fetch_platform_configs(struct platform_device *pdev)
> > {
> > struct stfsm *fsm = platform_get_drvdata(pdev);
> > struct device_node *np = pdev->dev.of_node;
> > + const struct stfsm_boot_dev *boot_dev;
> > + const struct of_device_id *match;
> > struct regmap *regmap;
> > - uint32_t boot_device_reg;
> > - uint32_t boot_device_spi;
> > - uint32_t boot_device; /* Value we read from *boot_device_reg */
> > + uint32_t boot_device; /* Value we read from the boot dev mode pins */
> > int ret;
> >
> > /* Booting from SPI NOR Flash is the default */
> > @@ -1998,21 +2046,18 @@ static void stfsm_fetch_platform_configs(struct platform_device *pdev)
> >
> > fsm->reset_por = of_property_read_bool(np, "st,reset-por");
> >
> > - /* Where in the syscon the boot device information lives */
> > - ret = of_property_read_u32(np, "st,boot-device-reg", &boot_device_reg);
> > - if (ret)
> > + match = of_match_node(stfsm_match, np);
> > + if (!match)
> > goto boot_device_fail;
> > + boot_dev = match->data;
> >
> > - /* Boot device value when booted from SPI NOR */
> > - ret = of_property_read_u32(np, "st,boot-device-spi", &boot_device_spi);
> > + ret = regmap_read(regmap, boot_dev->reg, &boot_device);
>
>
> ^^^ NULL pointer dereference for any existing DTB that uses the
> "st,spi-fsm" compatible string. So I'll NAK this patch as-is. Either we
> need to completely drop the "deprecated" compatible property (what's the
> point binding to it, if we're going to OOPS on it anyway), or else we
> need to maintain both methods (at least for whatever deprecation period
> is deemed acceptable).
Great spot Brian.
So, as I explained in reply to the cover-letter, this driver isn't
being used in anger yet. As the driver is still considered
in-progress I take the view that it's perfectly okay to remove the old
compatible string and not match on it at all.
I'll make the necessary changes and re-submit.
> > if (ret)
> > goto boot_device_fail;
> >
> > - ret = regmap_read(regmap, boot_device_reg, &boot_device);
> > - if (ret)
> > - goto boot_device_fail;
> > + boot_device &= boot_dev->mask;
> >
> > - if (boot_device != boot_device_spi)
> > + if (boot_device != boot_dev->spi)
> > fsm->booted_from_spi = false;
> >
> > return;
> > @@ -2156,12 +2201,6 @@ static int stfsmfsm_resume(struct device *dev)
> >
> > static SIMPLE_DEV_PM_OPS(stfsm_pm_ops, stfsmfsm_suspend, stfsmfsm_resume);
> >
> > -static const struct of_device_id stfsm_match[] = {
> > - { .compatible = "st,spi-fsm", },
> > - {},
> > -};
> > -MODULE_DEVICE_TABLE(of, stfsm_match);
> > -
> > static struct platform_driver stfsm_driver = {
> > .probe = stfsm_probe,
> > .remove = stfsm_remove,
>
> Brian
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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