From fdb7e884ad617f8aa69abdd7f39e3fdac85e081e Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Sat, 1 Jun 2019 00:37:56 +0200 Subject: i2c: iop: Use GPIO descriptors 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 Acked-by: Arnd Bergmann Acked-by: Dan Williams Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-iop3xx.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) (limited to 'drivers/i2c/busses/i2c-iop3xx.c') diff --git a/drivers/i2c/busses/i2c-iop3xx.c b/drivers/i2c/busses/i2c-iop3xx.c index a34cb3848280..eafc1a4d8656 100644 --- a/drivers/i2c/busses/i2c-iop3xx.c +++ b/drivers/i2c/busses/i2c-iop3xx.c @@ -38,7 +38,7 @@ #include #include #include -#include +#include #include "i2c-iop3xx.h" @@ -71,17 +71,16 @@ iop3xx_i2c_enable(struct i2c_algo_iop3xx_data *iop3xx_adap) /* * Every time unit enable is asserted, GPOD needs to be cleared - * on IOP3XX to avoid data corruption on the bus. + * on IOP3XX to avoid data corruption on the bus. We use the + * gpiod_set_raw_value() to make sure the 0 hits the hardware + * GPOD register. These descriptors are only passed along to + * the device if this is necessary. */ -#if defined(CONFIG_ARCH_IOP32X) || defined(CONFIG_ARCH_IOP33X) - if (iop3xx_adap->id == 0) { - gpio_set_value(7, 0); - gpio_set_value(6, 0); - } else { - gpio_set_value(5, 0); - gpio_set_value(4, 0); - } -#endif + if (iop3xx_adap->gpio_scl) + gpiod_set_raw_value(iop3xx_adap->gpio_scl, 0); + if (iop3xx_adap->gpio_sda) + gpiod_set_raw_value(iop3xx_adap->gpio_sda, 0); + /* NB SR bits not same position as CR IE bits :-( */ iop3xx_adap->SR_enabled = IOP3XX_ISR_ALD | IOP3XX_ISR_BERRD | @@ -434,6 +433,17 @@ iop3xx_i2c_probe(struct platform_device *pdev) goto free_adapter; } + adapter_data->gpio_scl = devm_gpiod_get_optional(&pdev->dev, + "scl", + GPIOD_ASIS); + if (IS_ERR(adapter_data->gpio_scl)) + return PTR_ERR(adapter_data->gpio_scl); + adapter_data->gpio_sda = devm_gpiod_get_optional(&pdev->dev, + "sda", + GPIOD_ASIS); + if (IS_ERR(adapter_data->gpio_sda)) + return PTR_ERR(adapter_data->gpio_sda); + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!res) { ret = -ENODEV; -- cgit v1.2.3-59-g8ed1b