On Wed, Jul 08, 2015 at 03:29:15PM +0200, Jan Luebbe wrote: > This is based on the code introduced to the kernel in > 5f9296ba21b3c395e53dd84e7ff9578f97f24295. > > Signed-off-by: Jan Luebbe <[email protected]> > --- > drivers/i2c/i2c.c | 161 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > include/i2c/i2c.h | 42 ++++++++++++++ > 2 files changed, 203 insertions(+) > > diff --git a/drivers/i2c/i2c.c b/drivers/i2c/i2c.c > index ebc7e23..e350ac5 100644 > --- a/drivers/i2c/i2c.c > +++ b/drivers/i2c/i2c.c > @@ -23,6 +23,7 @@ > #include <xfuncs.h> > #include <init.h> > #include <of.h> > +#include <gpio.h> > > #include <i2c/i2c.h> > > @@ -228,6 +229,133 @@ int i2c_write_reg(struct i2c_client *client, u32 addr, > const u8 *buf, u16 count) > } > EXPORT_SYMBOL(i2c_write_reg); > > +/* i2c bus recovery routines */ > +static int get_scl_gpio_value(struct i2c_adapter *adap) > +{ > + gpio_direction_input(adap->bus_recovery_info->scl_gpio); > + return gpio_get_value(adap->bus_recovery_info->scl_gpio); > +} > + > +static void set_scl_gpio_value(struct i2c_adapter *adap, int val) > +{ > + if (val) > + gpio_direction_input(adap->bus_recovery_info->scl_gpio); > + else > + gpio_direction_output(adap->bus_recovery_info->scl_gpio, 0); > +} > + > +static int get_sda_gpio_value(struct i2c_adapter *adap) > +{ > + return gpio_get_value(adap->bus_recovery_info->sda_gpio); > +} > + > +static int i2c_get_gpios_for_recovery(struct i2c_adapter *adap) > +{ > + struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; > + struct device_d *dev = &adap->dev; > + int ret = 0; > + > + ret = gpio_request_one(bri->scl_gpio, GPIOF_IN, "i2c-scl"); > + if (ret) { > + dev_warn(dev, "Can't get SCL gpio: %d\n", bri->scl_gpio); > + return ret; > + } > + > + if (bri->get_sda) { > + if (gpio_request_one(bri->sda_gpio, GPIOF_IN, "i2c-sda")) { > + /* work without SDA polling */ > + dev_warn(dev, "Can't get SDA gpio: %d. Not using SDA > polling\n", > + bri->sda_gpio); > + bri->get_sda = NULL; > + } > + } > + > + return ret; > +} > + > +static void i2c_put_gpios_for_recovery(struct i2c_adapter *adap) > +{ > + struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; > + > + if (bri->get_sda) > + gpio_free(bri->sda_gpio); > + > + gpio_free(bri->scl_gpio); > +} > + > +/* > + * We are generating clock pulses. ndelay() determines durating of clk > pulses. > + * We will generate clock with rate 100 KHz and so duration of both clock > levels > + * is: delay in ns = (10^6 / 100) / 2 > + */ > +#define RECOVERY_NDELAY 5000 > +#define RECOVERY_CLK_CNT 9 > + > +static int i2c_generic_recovery(struct i2c_adapter *adap) > +{ > + struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; > + int i = 0, val = 1, ret = 0; > + > + if (bri->prepare_recovery) > + bri->prepare_recovery(adap); > + > + /* > + * By this time SCL is high, as we need to give 9 falling-rising edges > + */ > + while (i++ < RECOVERY_CLK_CNT * 2) { > + if (val) { > + /* Break if SDA is high */ > + if (bri->get_sda && bri->get_sda(adap)) > + break; > + /* SCL shouldn't be low here */ > + if (!bri->get_scl(adap)) { > + dev_err(&adap->dev, > + "SCL is stuck low, exit recovery\n"); > + ret = -EBUSY; > + break; > + } > + } > + > + val = !val; > + bri->set_scl(adap, val); > + ndelay(RECOVERY_NDELAY); > + } > + > + if (bri->unprepare_recovery) > + bri->unprepare_recovery(adap); > + > + return ret; > +} > + > +int i2c_generic_scl_recovery(struct i2c_adapter *adap) > +{ > + adap->bus_recovery_info->set_scl(adap, 1); > + return i2c_generic_recovery(adap); > +} > + > +int i2c_generic_gpio_recovery(struct i2c_adapter *adap) > +{ > + int ret; > + > + ret = i2c_get_gpios_for_recovery(adap); > + if (ret) > + return ret; > + > + ret = i2c_generic_recovery(adap); > + i2c_put_gpios_for_recovery(adap); > + > + return ret; > +} > + > +int i2c_recover_bus(struct i2c_adapter *adap) > +{ > + if (!adap->bus_recovery_info) > + return -EOPNOTSUPP; > + > + dev_dbg(&adap->dev, "Trying i2c bus recovery\n"); > + return adap->bus_recovery_info->recover_bus(adap); > +} > + > /** > * i2c_new_device - instantiate one new I2C device > * > @@ -456,6 +584,39 @@ int i2c_add_numbered_adapter(struct i2c_adapter *adapter) > > list_add_tail(&adapter->list, &adapter_list); > > + /* bus recovery specific initialization */ > + if (adapter->bus_recovery_info) { > + struct i2c_bus_recovery_info *bri = adapter->bus_recovery_info; > + > + if (!bri->recover_bus) { > + dev_err(&adapter->dev, "No recover_bus() found, not > using recovery\n"); > + adapter->bus_recovery_info = NULL; > + goto exit_recovery; > + } > + > + /* Generic GPIO recovery */ > + if (bri->recover_bus == i2c_generic_gpio_recovery) {
This comparison to i2c_generic_gpio_recovery here forces the linker to always compile in gpio recovery support, even when it's unused in the compiled in drivers. I think we can do better here. Also, could you put the bus recovery support into a separate function so that we can call it wherever we need it? We might call it from other places later aswell. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
