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i2c: iop: Use GPIO descriptors

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The IOP3xx has some elaborate code to directly slam the
GPIO lines multiplexed with I2C down low before enablement,
apparently a workaround for a hardware bug found in the
early chips.

After consulting the developer documentation for IOP80321
and IOP80331 I can clearly see that this may be useful for
IOP80321 family (mach-iop32x) but it is highly dubious for
any 80331 series or later chip: in these chips the lines
are not multiplexed for UARTs.

We convert the code to pass optional GPIO descriptors
and register these only on the 80321-based boards where
it makes sense, optionally obtain them in the driver and
use the gpiod_set_raw_value() to ascertain the line gets
driven low when needed.

The GPIO driver does not give the GPIO chip a reasonable
label so the patch also adds that so that these machine
descriptor tables can be used.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Linus Walleij
2019-06-01 00:37:56 +02:00
committed by Wolfram Sang
parent ed7357c9f9
commit fdb7e884ad
10 changed files with 64 additions and 11 deletions
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2
arch/arm/include/asm/hardware/iop3xx.h
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@@ -305,6 +305,8 @@ extern struct platform_device iop3xx_dma_1_channel;
extern struct platform_device iop3xx_aau_channel;
extern struct platform_device iop3xx_i2c0_device;
extern struct platform_device iop3xx_i2c1_device;
extern struct gpiod_lookup_table iop3xx_i2c0_gpio_lookup;
extern struct gpiod_lookup_table iop3xx_i2c1_gpio_lookup;
#endif