Argh, the patch won't pass checkpatch because I brilliantly submitted it via gmail. Once the 2 issues (initializing SDA/SCL and platform structure) are discussed and agreed I'll resubmit the patch via git.
Thanks Eran On Sat, May 7, 2011 at 2:53 PM, Eran Duchan <[email protected]> wrote: > Hi guys, > > Following the discussion on the matter of i2c-gpio performance, I'm > submitting this very simple patch which adds i2c-bit-platform. Using > this driver, a platform can register callbacks called by i2c-bit-algo > so that it can modify GPIO pins directly or do pretty much anything > else. Besides style, I see 2 points for discussion: > > 1) Should the i2c-bit-platform call setscl/setsda passing state to 1 > (so that SDA/SCL are explicitly pulled high) on probe or should this > be implemented in the platforms which mandate this? In the patch I > left it up to the platform. > > 2) Which platform_data structure is passed to the driver? There are > three options: > 2.a) Currently in the patch - just expect a i2c_algo_bit_data > structure. No new structures introduced, but this does expose some > underlying bit-algo detail to the platform and does not elegantly > support passing any future i2c-bit-platform specific fields, should > they be required. > 2.b) Declare a new platform structure which has a i2c_algo_bit_data > member (for supporting future i2c-bit-platform fields). Solves the > future field issue but still exposes so bit-algo stuff to the platform > 2.c) Declare a new platform structure with members similar to > i2c_algo_bit_data, but only those who should be exposed to the > platform. The only downside to this is that any future change to > i2c_algo_bit_data may require change to this new platform structure. > > Tested on an MPC875 running @ 50MHz to achieve near perfect 100kHz I2C. > > Eran > > Signed-off-by: Eran Duchan <[email protected]> > --- > drivers/i2c/busses/Kconfig | 10 +++ > drivers/i2c/busses/Makefile | 1 + > drivers/i2c/busses/i2c-bit-platform.c | 105 > +++++++++++++++++++++++++++++++++ > 3 files changed, 116 insertions(+), 0 deletions(-) > create mode 100644 drivers/i2c/busses/i2c-bit-platform.c > > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig > index 3a6321c..f6c6b8c 100644 > --- a/drivers/i2c/busses/Kconfig > +++ b/drivers/i2c/busses/Kconfig > @@ -365,6 +365,16 @@ config I2C_GPIO > This is a very simple bitbanging I2C driver utilizing the > arch-neutral GPIO API to control the SCL and SDA lines. > > +config I2C_BIT_PLATFORM > + tristate "I2c-bit-algo as platform device" > + select I2C_ALGOBIT > + help > + An I2C bus adapter which delegates the bit-algo callback > registration > + to the platform. Useful in cases where existing adapters such as > + i2c-gpio are too slow. Keep in mind that no resource locking of any > kind > + is performed by the adapter or algo, so any such contention must be > + handled by the platform. > + > config I2C_HIGHLANDER > tristate "Highlander FPGA SMBus interface" > depends on SH_HIGHLANDER > diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile > index 84cb16a..65bced4 100644 > --- a/drivers/i2c/busses/Makefile > +++ b/drivers/i2c/busses/Makefile > @@ -35,6 +35,7 @@ obj-$(CONFIG_I2C_CPM) += i2c-cpm.o > obj-$(CONFIG_I2C_DAVINCI) += i2c-davinci.o > obj-$(CONFIG_I2C_DESIGNWARE) += i2c-designware.o > obj-$(CONFIG_I2C_GPIO) += i2c-gpio.o > +obj-$(CONFIG_I2C_BIT_PLATFORM) += i2c-bit-platform.o > obj-$(CONFIG_I2C_HIGHLANDER) += i2c-highlander.o > obj-$(CONFIG_I2C_IBM_IIC) += i2c-ibm_iic.o > obj-$(CONFIG_I2C_IMX) += i2c-imx.o > diff --git a/drivers/i2c/busses/i2c-bit-platform.c > b/drivers/i2c/busses/i2c-bit-platform.c > new file mode 100644 > index 0000000..cb98006 > --- /dev/null > +++ b/drivers/i2c/busses/i2c-bit-platform.c > @@ -0,0 +1,105 @@ > +/* > + i2c-bit-algo as platform device > + Delegates the bit-algo callback registration to the platform > + > + Copyright (C) 2011 Eran Duchan <[email protected]> > + > + This program is free software; you can redistribute it and/or modify > + it under the terms of the GNU General Public License as published by > + the Free Software Foundation; either version 2 of the License, or > + (at your option) any later version. > +*/ > + > +#include <linux/i2c.h> > +#include <linux/i2c-algo-bit.h> > +#include <linux/slab.h> > + > +static int __devinit i2c_bit_platform_probe(struct platform_device *pdev) > +{ > + struct i2c_algo_bit_data *bit_data; > + struct i2c_adapter *adap; > + int ret; > + > + if (pdev->dev.platform_data == NULL) > + ret = -ENXIO; > + > + bit_data = pdev->dev.platform_data; > + > + ret = -ENOMEM; > + adap = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL); > + if (adap == NULL) > + goto err_alloc_adap; > + > + adap->owner = THIS_MODULE; > + adap->algo_data = bit_data; > + adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD; > + adap->dev.parent = &pdev->dev; > + > + snprintf(adap->name, sizeof(adap->name), "i2c-bit-platform%d", > + pdev->id); > + adap->name[sizeof(adap->name) - 1] = '\0'; > + > + /* > + * If "dev->id" is negative we consider it as zero. > + * The reason to do so is to avoid sysfs names that only make > + * sense when there are multiple adapters. > + */ > + adap->nr = (pdev->id != -1) ? pdev->id : 0; > + ret = i2c_bit_add_numbered_bus(adap); > + if (ret) > + goto err_add_bus; > + > + platform_set_drvdata(pdev, adap); > + > + return 0; > + > +err_add_bus: > +err_alloc_adap: > + > + kfree(adap); > + > + return ret; > +} > + > +static int __devexit i2c_bit_platform_remove(struct platform_device *pdev) > +{ > + struct i2c_adapter *adap; > + > + adap = platform_get_drvdata(pdev); > + > + i2c_del_adapter(adap); > + kfree(adap); > + > + return 0; > +} > + > +static struct platform_driver i2c_bit_platform_driver = { > + .driver = { > + .name = "i2c-bit-platform", > + .owner = THIS_MODULE, > + }, > + .probe = i2c_bit_platform_probe, > + .remove = __devexit_p(i2c_bit_platform_remove), > +}; > + > +static int __init i2c_bit_platform_init(void) > +{ > + int ret; > + > + ret = platform_driver_register(&i2c_bit_platform_driver); > + if (ret) > + printk(KERN_ERR "i2c-bit-platform: probe failed: %d\n", ret); > + > + return ret; > +} > +subsys_initcall(i2c_bit_platform_init); > + > +static void __exit i2c_bit_platform_exit(void) > +{ > + platform_driver_unregister(&i2c_bit_platform_driver); > +} > +module_exit(i2c_bit_platform_exit); > + > +MODULE_AUTHOR("Eran Duchan <[email protected]>"); > +MODULE_DESCRIPTION("Thin platform adapter for i2c-bit-algo"); > +MODULE_LICENSE("GPL"); > -- > 1.7.0.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
