On Thu, Nov 10, 2016 at 02:35:46PM +0100, Michal Simek wrote:
> On 8.11.2016 11:19, Maxime Ripard wrote:
> > Add a bus driver for bitbanging a 1-Wire bus over a GPIO.
> >
> > Signed-off-by: Maxime Ripard <maxime.rip...@free-electrons.com>
> > ---
> > drivers/w1/Kconfig | 6 ++-
> > drivers/w1/Makefile | 1 +-
> > drivers/w1/w1-gpio.c | 160 ++++++++++++++++++++++++++++++++++++++++++++-
> > 3 files changed, 167 insertions(+), 0 deletions(-)
> > create mode 100644 drivers/w1/w1-gpio.c
> >
> > diff --git a/drivers/w1/Kconfig b/drivers/w1/Kconfig
> > index 0c056b4c06a9..ccc3ae15db86 100644
> > --- a/drivers/w1/Kconfig
> > +++ b/drivers/w1/Kconfig
> > @@ -12,6 +12,12 @@ config W1
> >
> > if W1
> >
> > +config W1_GPIO
> > + bool "Enable 1-Wire GPIO bitbanging"
> > + depends on DM_GPIO
> > + help
> > + Emulate a 1-Wire bus using a GPIO.
> > +
> > endif
> >
> > endmenu
> > diff --git a/drivers/w1/Makefile b/drivers/w1/Makefile
> > index 26820fa209e1..7fd8697f8419 100644
> > --- a/drivers/w1/Makefile
> > +++ b/drivers/w1/Makefile
> > @@ -1,2 +1,3 @@
> > obj-$(CONFIG_W1) += w1-uclass.o
> >
> > +obj-$(CONFIG_W1_GPIO) += w1-gpio.o
> > diff --git a/drivers/w1/w1-gpio.c b/drivers/w1/w1-gpio.c
> > new file mode 100644
> > index 000000000000..091849162533
> > --- /dev/null
> > +++ b/drivers/w1/w1-gpio.c
> > @@ -0,0 +1,160 @@
> > +/*
> > + * Copyright (c) 2015 Free Electrons
> > + * Copyright (c) 2015 NextThing Co
> > + *
> > + * Maxime Ripard <maxime.rip...@free-electrons.com>
> > + *
> > + * SPDX-License-Identifier: GPL-2.0+
> > + */
> > +
> > +#include <common.h>
> > +#include <dm.h>
> > +#include <w1.h>
> > +
> > +#include <asm/gpio.h>
> > +
> > +
> > +#define W1_TIMING_A 6
> > +#define W1_TIMING_B 64
> > +#define W1_TIMING_C 60
> > +#define W1_TIMING_D 10
> > +#define W1_TIMING_E 9
> > +#define W1_TIMING_F 55
> > +#define W1_TIMING_G 0
> > +#define W1_TIMING_H 480
> > +#define W1_TIMING_I 70
> > +#define W1_TIMING_J 410
> > +
> > +struct w1_gpio_pdata {
> > + struct gpio_desc gpio;
> > + u64 search_id;
> > +};
> > +
> > +static bool w1_gpio_read_bit(struct udevice *dev)
> > +{
> > + struct w1_gpio_pdata *pdata = dev_get_platdata(dev);
> > + int val;
> > +
> > + dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_OUT);
> > + udelay(W1_TIMING_A);
> > +
> > + dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_IN);
> > + udelay(W1_TIMING_E);
> > +
> > + val = dm_gpio_get_value(&pdata->gpio);
> > + udelay(W1_TIMING_F);
> > +
> > + return val;
> > +}
> > +
> > +static u8 w1_gpio_read_byte(struct udevice *dev)
> > +{
> > + int i;
> > + u8 ret = 0;
> > +
> > + for (i = 0; i < 8; ++i)
> > + ret |= (w1_gpio_read_bit(dev) ? 1 : 0) << i;
> > +
> > + return ret;
> > +}
> > +
> > +static void w1_gpio_write_bit(struct udevice *dev, bool bit)
> > +{
> > + struct w1_gpio_pdata *pdata = dev_get_platdata(dev);
> > +
> > + dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_OUT);
> > +
> > + bit ? udelay(W1_TIMING_A) : udelay(W1_TIMING_C);
> > +
> > + dm_gpio_set_value(&pdata->gpio, 1);
> > +
> > + bit ? udelay(W1_TIMING_B) : udelay(W1_TIMING_D);
> > +}
> > +
> > +static void w1_gpio_write_byte(struct udevice *dev, u8 byte)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < 8; ++i)
> > + w1_gpio_write_bit(dev, (byte >> i) & 0x1);
> > +}
> > +
> > +static bool w1_gpio_reset(struct udevice *dev)
> > +{
> > + struct w1_gpio_pdata *pdata = dev_get_platdata(dev);
> > + int val;
> > +
> > + dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
> > + udelay(W1_TIMING_G);
> > +
> > + dm_gpio_set_value(&pdata->gpio, 0);
> > + udelay(W1_TIMING_H);
> > +
> > + dm_gpio_set_dir_flags(&pdata->gpio, GPIOD_IS_IN);
> > + udelay(W1_TIMING_I);
> > +
> > + val = dm_gpio_get_value(&pdata->gpio);
> > + udelay(W1_TIMING_J);
> > +
> > + return val;
> > +}
> > +
> > +static u8 w1_gpio_triplet(struct udevice *dev, bool bdir)
> > +{
> > + u8 id_bit = w1_gpio_read_bit(dev);
> > + u8 comp_bit = w1_gpio_read_bit(dev);
> > + u8 retval;
> > +
> > + if (id_bit && comp_bit)
> > + return 0x03; /* error */
> > +
> > + if (!id_bit && !comp_bit) {
> > + /* Both bits are valid, take the direction given */
> > + retval = bdir ? 0x04 : 0;
> > + } else {
> > + /* Only one bit is valid, take that direction */
> > + bdir = id_bit;
> > + retval = id_bit ? 0x05 : 0x02;
> > + }
> > +
> > + w1_gpio_write_bit(dev, bdir);
> > + return retval;
> > +}
> > +
> > +
> > +static const struct w1_ops w1_gpio_ops = {
> > + .read_byte = w1_gpio_read_byte,
> > + .reset = w1_gpio_reset,
> > + .triplet = w1_gpio_triplet,
> > + .write_byte = w1_gpio_write_byte,
> > +};
> > +
> > +static int w1_gpio_ofdata_to_platdata(struct udevice *dev)
> > +{
> > + struct w1_gpio_pdata *pdata = dev_get_platdata(dev);
> > + int ret;
> > +
> > + ret = gpio_request_by_name(dev, "gpios", 0, &pdata->gpio, 0);
> > + if (ret < 0)
> > + goto error;
> > +
> > + return 0;
> > +
> > +error:
> > + printf("Error claiming GPIO %d\n", ret);
> > + return ret;
> > +};
> > +
> > +static const struct udevice_id w1_gpio_id[] = {
> > + { "w1-gpio", 0 },
> > + { },
> > +};
> > +
> > +U_BOOT_DRIVER(w1_gpio_drv) = {
> > + .id = UCLASS_W1,
> > + .name = "w1_gpio_drv",
> > + .of_match = w1_gpio_id,
> > + .ofdata_to_platdata = w1_gpio_ofdata_to_platdata,
> > + .ops = &w1_gpio_ops,
> > + .platdata_auto_alloc_size = sizeof(struct w1_gpio_pdata),
> > +};
> >
>
> Has someone test this on different HW?I didn't, but it looks pretty generic. The only thing you have to make sure is that you can respect the rather tight timing constraints of the bus. That rules out a GPIO on an I2C expander for example. > As I went through the series will be good to have cmd/w1.c to be > able to test that devices. Ack. Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
signature.asc
Description: PGP signature
_______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
