On Thu, Jan 24, 2013 at 04:06:37PM +0530, Viresh Kumar wrote: > Add i2c bus recovery infrastructure to i2c adapters as specified in the i2c > protocol Rev. 03 section 3.1.16 titled "Bus clear". > > http://www.nxp.com/documents/user_manual/UM10204.pdf > > Sometimes during operation i2c bus hangs and we need to give dummy clocks to > slave device to start the transfer again. Now we may have capability in the > bus > controller to generate these clocks or platform may have gpio pins which can > be > toggled to generate dummy clocks. This patch supports both. > > This patch also adds in generic bus recovery routines gpio or scl line based > which can be used by bus controller. In addition controller driver may provide > its own version of the bus recovery routine. > > This doesn't support multi-master recovery for now. > > Reviewed-by: Paul Carpenter <[email protected]> > Signed-off-by: Viresh Kumar <[email protected]> > --- > Most number of versions for any patchset i submitted :) > > V8->V9: > - removed skip_sda_polling variable > - simplified/fixed i2c_generic_recovery() routine > - added new routine i2c_recover_bus() > - added gpio_is_valid() checks over scl and sda gpios > - code is rearranged at places (based on Wolfram's comments) > > drivers/i2c/i2c-core.c | 155 > +++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/i2c.h | 39 +++++++++++++ > 2 files changed, 194 insertions(+) > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index e388590..8076e52 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -27,7 +27,9 @@ > > #include <linux/module.h> > #include <linux/kernel.h> > +#include <linux/delay.h> > #include <linux/errno.h> > +#include <linux/gpio.h> > #include <linux/slab.h> > #include <linux/i2c.h> > #include <linux/init.h> > @@ -109,6 +111,127 @@ static int i2c_device_uevent(struct device *dev, struct > kobj_uevent_env *env) > #define i2c_device_uevent NULL > #endif /* CONFIG_HOTPLUG */ > > +/* i2c bus recovery routines */ > +#define RECOVERY_CLK_CNT 9 > +#define DEFAULT_CLK_RATE 100 /* KHz */
RECOVERY_CLK_RATE
> +/* 10^6/KHz for delay in ns */
> +unsigned long clk_delay = DIV_ROUND_UP(1000000, DEFAULT_CLK_RATE * 2);
Since all inputs are constant values, the result will be a constant as
well. We might even get rid of this variable altogether.
> +
> +static int get_scl_gpio_value(struct i2c_adapter *adap)
> +{
> + return gpio_get_value(adap->bus_recovery_info->scl_gpio);
> +}
> +
> +static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
> +{
> + gpio_set_value(adap->bus_recovery_info->scl_gpio, val);
> +}
> +
> +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 *dev = &adap->dev;
> + int ret = 0;
> +
> + ret = gpio_request_one(bri->scl_gpio, GPIOF_OPEN_DRAIN |
> + GPIOF_OUT_INIT_HIGH, "i2c-scl");
> + if (ret) {
> + dev_warn(dev, "gpio request fail: %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: %d. Skip 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);
> +}
> +
> +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(bri);
> +
> + /*
> + * By this time SCL is high, as we need to give 9 falling-rising edges
> + */
> + while (i++ < RECOVERY_CLK_CNT * 2) {
> + /* SCL shouldn't be low here */
> + if (val && !bri->get_scl(adap)) {
> + dev_err(&adap->dev, "SCL is stuck Low exit recovery\n");
s/Low/low/
> + ret = -EBUSY;
> + goto unprepare;
> + }
> +
> + val = !val;
> + bri->set_scl(adap, val);
> + ndelay(clk_delay);
> +
> + /* break if sda got high, check only when scl line is high */
> + if (bri->get_sda && val)
> + if (bri->get_sda(adap))
> + break;
if (val && bri->get_sda && bri->get_sda(adap)
break;
Didn't we agree to move the SDA check before the SCL setting?
> + }
> +
> +unprepare:
> + if (bri->unprepare_recovery)
> + bri->unprepare_recovery(bri);
> +
> + 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, "try i2c bus recovery\n");
s/try/trying/
> + return adap->bus_recovery_info->recover_bus(adap);
> +}
> +
> static int i2c_device_probe(struct device *dev)
> {
> struct i2c_client *client = i2c_verify_client(dev);
> @@ -902,6 +1025,38 @@ static int i2c_register_adapter(struct i2c_adapter
> *adap)
> "Failed to create compatibility class link\n");
> #endif
>
> + /* bus recovery specific initialization */
> + if (adap->bus_recovery_info) {
> + struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
> +
> + if (!bri->recover_bus) {
> + dev_err(&adap->dev, "Invalid recover_bus(), skip
> recovery\n");
s/Invalid/No/
s/skip/not using/
The latter for all later occurences, too.
> + adap->bus_recovery_info = NULL;
> + goto exit_recovery;
> + }
> +
> + /* GPIO recovery */
> + if (bri->recover_bus == i2c_generic_gpio_recovery) {
> + if (!gpio_is_valid(bri->scl_gpio)) {
> + dev_err(&adap->dev, "Invalid scl gpio, skip
> recovery\n");
> + adap->bus_recovery_info = NULL;
> + goto exit_recovery;
> + }
> +
> + if (gpio_is_valid(bri->sda_gpio))
> + bri->get_sda = get_sda_gpio_value;
> + else
> + bri->get_sda = NULL;
> +
> + bri->get_scl = get_scl_gpio_value;
> + bri->set_scl = set_scl_gpio_value;
> + } else if (!bri->set_scl) {
> + dev_warn(&adap->dev,
> + "set_scl() is must for scl recovery\n");
What about get_scl. You don't check here, but you don't check when you
use it above.
> + }
> + }
> +
> +exit_recovery:
> /* create pre-declared device nodes */
> if (adap->nr < __i2c_first_dynamic_bus_num)
> i2c_scan_static_board_info(adap);
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index d0c4db7..da9358b 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -370,6 +370,43 @@ struct i2c_algorithm {
> u32 (*functionality) (struct i2c_adapter *);
> };
>
> +/**
> + * struct i2c_bus_recovery_info - I2C bus recovery information
> + * @recover_bus: Recover routine. Either pass driver's recover_bus()
> routine, or
> + * i2c_generic_scl_recovery() or i2c_generic_gpio_recovery().
> + * @get_scl: This gets current value of scl line. Mandatory for generic SCL
> + * recovery. Used internally for generic GPIO recovery.
> + * @set_scl: This sets/clears scl line. Mandatory for generic SCL recovery.
> Used
> + * internally for generic GPIO recovery.
> + * @get_sda: This gets current value of sda line. Optional for generic SCL
> + * recovery. Used internally, if sda_gpio != -1, for generic GPIO
> recovery.
s/!= -1/is a valid GPIO/
> + * @prepare_recovery: This will be called before starting recovery. Platform
> may
> + * configure padmux here for sda/scl line or something else they want.
> + * @unprepare_recovery: This will be called after completing recovery.
> Platform
> + * may configure padmux here for sda/scl line or something else they want.
> + * @scl_gpio: gpio number of the scl line. Only required for GPIO recovery.
> + * @sda_gpio: gpio number of the sda line. Only required for GPIO recovery.
> + */
> +struct i2c_bus_recovery_info {
> + int (*recover_bus)(struct i2c_adapter *);
> +
> + int (*get_scl)(struct i2c_adapter *);
> + void (*set_scl)(struct i2c_adapter *, int val);
> + int (*get_sda)(struct i2c_adapter *);
> +
> + void (*prepare_recovery)(struct i2c_bus_recovery_info *bri);
> + void (*unprepare_recovery)(struct i2c_bus_recovery_info *bri);
> +
> + /* gpio recovery */
> + unsigned scl_gpio;
> + unsigned sda_gpio;
> +};
> +
> +/* Generic recovery routines */
> +int i2c_generic_gpio_recovery(struct i2c_adapter *adap);
> +int i2c_generic_scl_recovery(struct i2c_adapter *adap);
> +int i2c_recover_bus(struct i2c_adapter *adap);
> +
> /*
> * i2c_adapter is the structure used to identify a physical i2c bus along
> * with the access algorithms necessary to access it.
> @@ -393,6 +430,8 @@ struct i2c_adapter {
>
> struct mutex userspace_clients_lock;
> struct list_head userspace_clients;
> +
> + struct i2c_bus_recovery_info *bus_recovery_info;
> };
> #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
Regards,
Wolfram
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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