[i2c] [PATCH 2/2] i2c: Add devtree-aware iic support for PPC4xx

Grant Likely grant.likely at secretlab.ca
Mon Oct 15 18:46:04 CEST 2007


On 10/15/07, Stefan Roese <sr at denx.de> wrote:
> This patch reworks existing ibm-iic driver to support of_platform_device
> and enables it to talk to device tree directly. The "old" OCP interface
> for arch/ppc is still supported via #ifdef's and shall be removed when
> arch/ppc is gone in a few months.
>
> This is done to enable I2C support for the PPC4xx platforms now
> being moved from arch/ppc (ocp) to arch/powerpc (of).

May I suggest another approach?

Take a look at driver/video/xilinxfb.c.
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=drivers/video/xilinxfb.c;h=6ef99b2d13ca6f8a4809d5914cbab6309255b3e3;hb=287e5d6fcccfa38b953cebe307e1ddfd32363355

That driver supports both the platform bus and the of_platform bus.
(xilinxfb_of_probe and xilinxfb_platform_probe) and both functions
call a common setup routine (xilinxfb_assign; but I probably should
have named it xilinxfb_setup).

Rather than writing an entirely new probe function; I suggest
splitting the binding code from the initialization code.  The binding
code translates from the device description (be that platform bus,
of_platform bus, ocp, whatever) to the values the driver needs.  The
initialization code needs to do the same thing for both bus bindings,
and the bus binding code is only concerned with getting the
appropriate values from the device descripton.

It's a little bit more work to refactor the driver to follow this
mode, but it results in far less code which is easier to review and
understand.  Plus the device description is incomplete, you can bail
out before you start allocating and mapping memory that needs to be
unwound.

Cheers,
g.

>
> Signed-off-by: Stefan Roese <sr at denx.de>
> ---
>  drivers/i2c/busses/Kconfig       |    2 +-
>  drivers/i2c/busses/i2c-ibm_iic.c |  209 +++++++++++++++++++++++++++++++++++++-
>  drivers/i2c/busses/i2c-ibm_iic.h |    2 +
>  3 files changed, 211 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index de95c75..a47b5e6 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -241,7 +241,7 @@ config I2C_PIIX4
>
>  config I2C_IBM_IIC
>         tristate "IBM PPC 4xx on-chip I2C interface"
> -       depends on IBM_OCP
> +       depends on 4xx
>         help
>           Say Y here if you want to use IIC peripheral found on
>           embedded IBM PPC 4xx based systems.
> diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
> index 956b947..78c6bf4 100644
> --- a/drivers/i2c/busses/i2c-ibm_iic.c
> +++ b/drivers/i2c/busses/i2c-ibm_iic.c
> @@ -39,8 +39,13 @@
>  #include <asm/io.h>
>  #include <linux/i2c.h>
>  #include <linux/i2c-id.h>
> +
> +#ifdef CONFIG_PPC_MERGE
> +#include <linux/of_platform.h>
> +#else
>  #include <asm/ocp.h>
>  #include <asm/ibm4xx.h>
> +#endif
>
>  #include "i2c-ibm_iic.h"
>
> @@ -57,6 +62,10 @@ static int iic_force_fast;
>  module_param(iic_force_fast, bool, 0);
>  MODULE_PARM_DESC(iic_fast_poll, "Force fast mode (400 kHz)");
>
> +#ifdef CONFIG_PPC_MERGE
> +static int device_idx = -1;
> +#endif
> +
>  #define DBG_LEVEL 0
>
>  #ifdef DBG
> @@ -660,8 +669,205 @@ static inline u8 iic_clckdiv(unsigned int opb)
>  /*
>   * Register single IIC interface
>   */
> -static int __devinit iic_probe(struct ocp_device *ocp){
>
> +#ifdef CONFIG_PPC_MERGE
> +/*
> + * device-tree (of) when used from arch/powerpc
> + */
> +static int __devinit iic_probe(struct of_device *ofdev,
> +                              const struct of_device_id *match)
> +{
> +       struct ibm_iic_private* dev;
> +       struct i2c_adapter* adap;
> +       struct device_node *np;
> +       int ret = -ENODEV;
> +       int  irq, len;
> +       const u32 *prop;
> +       struct resource res;
> +
> +       np = ofdev->node;
> +       if (!(dev = kzalloc(sizeof(*dev), GFP_KERNEL))) {
> +               printk(KERN_CRIT "ibm-iic(%s): failed to allocate device data\n",
> +                      np->full_name);
> +               return -ENOMEM;
> +       }
> +
> +       dev_set_drvdata(&ofdev->dev, dev);
> +
> +       dev->np = np;
> +       irq = irq_of_parse_and_map(np, 0);
> +
> +       if (of_address_to_resource(np, 0, &res)) {
> +               printk(KERN_ERR "ibd-iic(%s): Can't get registers address\n",
> +                      np->full_name);
> +               goto fail1;
> +       }
> +       dev->paddr = res.start;
> +
> +       if (!request_mem_region(dev->paddr, sizeof(struct iic_regs), "ibm_iic")) {
> +               ret = -EBUSY;
> +               goto fail1;
> +       }
> +       dev->vaddr = ioremap(dev->paddr, sizeof(struct iic_regs));
> +
> +       if (dev->vaddr == NULL) {
> +               printk(KERN_CRIT "ibm-iic(%s): failed to ioremap device regs\n",
> +                      dev->np->full_name);
> +               ret = -ENXIO;
> +               goto fail2;
> +       }
> +
> +       init_waitqueue_head(&dev->wq);
> +
> +       dev->irq = iic_force_poll ? -1 : (irq == NO_IRQ) ? -1 : irq;
> +       if (dev->irq >= 0){
> +               /* Disable interrupts until we finish initialization,
> +                * assumes level-sensitive IRQ setup...
> +                */
> +               iic_interrupt_mode(dev, 0);
> +               if (request_irq(dev->irq, iic_handler, 0, "IBM IIC", dev)) {
> +                       printk(KERN_ERR "ibm-iic(%s): request_irq %d failed\n",
> +                              dev->np->full_name, dev->irq);
> +                       /* Fallback to the polling mode */
> +                       dev->irq = -1;
> +               }
> +       }
> +
> +       if (dev->irq < 0)
> +               printk(KERN_WARNING "ibm-iic(%s): using polling mode\n",
> +                      dev->np->full_name);
> +
> +       /* Board specific settings */
> +       prop = of_get_property(np, "iic-mode", &len);
> +       /* use 400kHz only if stated in dts, 100kHz otherwise */
> +       dev->fast_mode = (prop && (*prop == 400));
> +       /* clckdiv is the same for *all* IIC interfaces,
> +        * but I'd rather make a copy than introduce another global. --ebs
> +        */
> +       /* Parent bus should have frequency filled */
> +       prop = of_get_property(of_get_parent(np), "clock-frequency", &len);
> +       if (prop == NULL) {
> +               printk(KERN_ERR
> +                      "ibm-iic(%s):no clock-frequency prop on parent bus!\n",
> +                      dev->np->full_name);
> +               goto fail;
> +       }
> +
> +       dev->clckdiv = iic_clckdiv(*prop);
> +       DBG("%s: clckdiv = %d\n", dev->np->full_name, dev->clckdiv);
> +
> +       /* Initialize IIC interface */
> +       iic_dev_init(dev);
> +
> +       /* Register it with i2c layer */
> +       adap = &dev->adap;
> +       adap->dev.parent = &ofdev->dev;
> +       strcpy(adap->name, "IBM IIC");
> +       i2c_set_adapdata(adap, dev);
> +       adap->id = I2C_HW_OCP;
> +       adap->class = I2C_CLASS_HWMON;
> +       adap->algo = &iic_algo;
> +       adap->client_register = NULL;
> +       adap->client_unregister = NULL;
> +       adap->timeout = 1;
> +       adap->retries = 1;
> +
> +       dev->idx = ++device_idx;
> +       adap->nr = dev->idx;
> +       if ((ret = i2c_add_numbered_adapter(adap)) < 0) {
> +               printk(KERN_CRIT"ibm-iic(%s): failed to register i2c adapter\n",
> +                      dev->np->full_name);
> +               goto fail;
> +       }
> +
> +       printk(KERN_INFO "ibm-iic(%s): using %s mode\n", dev->np->full_name,
> +              dev->fast_mode ?
> +              "fast (400 kHz)" : "standard (100 kHz)");
> +
> +       return 0;
> +
> +fail:
> +       if (dev->irq >= 0){
> +               iic_interrupt_mode(dev, 0);
> +               free_irq(dev->irq, dev);
> +       }
> +
> +       iounmap(dev->vaddr);
> +fail2:
> +       release_mem_region(dev->paddr, sizeof(struct iic_regs));
> +fail1:
> +       dev_set_drvdata(&ofdev->dev, NULL);
> +       kfree(dev);
> +
> +       return ret;
> +}
> +
> +/*
> + * Cleanup initialized IIC interface
> + */
> +static int __devexit iic_remove(struct of_device *ofdev)
> +{
> +       struct ibm_iic_private *dev =
> +               (struct ibm_iic_private *)dev_get_drvdata(&ofdev->dev);
> +       BUG_ON(dev == NULL);
> +       if (i2c_del_adapter(&dev->adap)){
> +               printk(KERN_CRIT "ibm-iic(%s): failed to delete i2c adapter\n",
> +                      dev->np->full_name);
> +               /* That's *very* bad, just shutdown IRQ ... */
> +               if (dev->irq >= 0){
> +                       iic_interrupt_mode(dev, 0);
> +                       free_irq(dev->irq, dev);
> +                       dev->irq = -1;
> +               }
> +       } else {
> +               if (dev->irq >= 0){
> +                       iic_interrupt_mode(dev, 0);
> +                       free_irq(dev->irq, dev);
> +               }
> +               iounmap(dev->vaddr);
> +               release_mem_region(dev->paddr, sizeof(struct iic_regs));
> +               kfree(dev);
> +       }
> +       return 0;
> +}
> +
> +static struct of_device_id ibm_iic_match[] = {
> +       {
> +               .type = "i2c",
> +               .compatible = "ibm,iic",
> +       },
> +       {},
> +};
> +
> +MODULE_DEVICE_TABLE(of, ibm_iic_match);
> +
> +static struct of_platform_driver ibm_iic_driver = {
> +       .name = "ibm-iic",
> +       .match_table = ibm_iic_match,
> +       .probe = iic_probe,
> +       .remove = iic_remove,
> +#if defined(CONFIG_PM)
> +       .suspend = NULL,
> +       .resume = NULL,
> +#endif
> +};
> +
> +static int __init iic_init(void)
> +{
> +       printk(KERN_INFO "IBM IIC driver v" DRIVER_VERSION "\n");
> +       return of_register_platform_driver(&ibm_iic_driver);
> +}
> +
> +static void __exit iic_exit(void)
> +{
> +       of_unregister_platform_driver(&ibm_iic_driver);
> +}
> +#else
> +/*
> + * OCP when used from arch/ppc
> + */
> +static int __devinit iic_probe(struct ocp_device *ocp)
> +{
>         struct ibm_iic_private* dev;
>         struct i2c_adapter* adap;
>         struct ocp_func_iic_data* iic_data = ocp->def->additions;
> @@ -828,6 +1034,7 @@ static void __exit iic_exit(void)
>  {
>         ocp_unregister_driver(&ibm_iic_driver);
>  }
> +#endif /* CONFIG_PPC_MERGE */
>
>  module_init(iic_init);
>  module_exit(iic_exit);
> diff --git a/drivers/i2c/busses/i2c-ibm_iic.h b/drivers/i2c/busses/i2c-ibm_iic.h
> index fdaa482..c15b091 100644
> --- a/drivers/i2c/busses/i2c-ibm_iic.h
> +++ b/drivers/i2c/busses/i2c-ibm_iic.h
> @@ -50,6 +50,8 @@ struct ibm_iic_private {
>         int irq;
>         int fast_mode;
>         u8  clckdiv;
> +       struct device_node *np;
> +       phys_addr_t paddr;
>  };
>
>  /* IICx_CNTL register */
> --
> 1.5.3.4
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev at ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-dev
>


-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
grant.likely at secretlab.ca
(403) 399-0195



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