On 24/01/11 10:50, Wolfram Sang wrote:
> Currently only supporting the PIOQUEUE-mode, because DMA-support for
> this platform is not yet available. When it becomes available and
> support has been added to this driver, it will also be suitable for
> i.MX23 and STMP3xxx.
>
> Signed-off-by: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
> Cc: Ben Dooks <ben-linux@xxxxxxxxx>
> ---
> drivers/i2c/busses/Kconfig | 10 +
> drivers/i2c/busses/Makefile | 1 +
> drivers/i2c/busses/i2c-mxs.c | 383 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 394 insertions(+), 0 deletions(-)
> create mode 100644 drivers/i2c/busses/i2c-mxs.c
>
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 3a6321c..25e2dc7 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -452,6 +452,16 @@ config I2C_MV64XXX
> This driver can also be built as a module. If so, the module
> will be called i2c-mv64xxx.
>
> +config I2C_MXS
> + tristate "Freescale i.MX28 I2C interface"
> + depends on SOC_IMX28
> + help
> + Say Y here if you want to use the I2C bus controller on
> + the Freescale i.MX28 processors.
> +
> + This driver can also be built as a module. If so, the module
> + will be called i2c-mxs.
> +
> config I2C_NOMADIK
> tristate "ST-Ericsson Nomadik/Ux500 I2C Controller"
> depends on PLAT_NOMADIK
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 84cb16a..f415132 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -43,6 +43,7 @@ obj-$(CONFIG_I2C_IOP3XX) += i2c-iop3xx.o
> obj-$(CONFIG_I2C_IXP2000) += i2c-ixp2000.o
> obj-$(CONFIG_I2C_MPC) += i2c-mpc.o
> obj-$(CONFIG_I2C_MV64XXX) += i2c-mv64xxx.o
> +obj-$(CONFIG_I2C_MXS) += i2c-mxs.o
> obj-$(CONFIG_I2C_NOMADIK) += i2c-nomadik.o
> obj-$(CONFIG_I2C_NUC900) += i2c-nuc900.o
> obj-$(CONFIG_I2C_OCORES) += i2c-ocores.o
> diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
> new file mode 100644
> index 0000000..b80233b
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-mxs.c
> @@ -0,0 +1,383 @@
> +/*
> + * Freescale MXS I2C bus driver
> + *
> + * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
> + *
> + * based on a (broken) driver which was:
> + *
> + * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
> + *
> + * TODO: add dma-support if platform-support for it is available
> + *
> + * 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/slab.h>
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/completion.h>
> +#include <linux/platform_device.h>
> +#include <linux/jiffies.h>
> +#include <linux/io.h>
> +
> +#include <mach/common.h>
do we actually use anything from the above?
> +struct mxs_i2c_dev {
> + struct device *dev;
> + void __iomem *regs;
> + struct completion cmd_complete;
> + u32 cmd_err;
> + struct i2c_adapter adapter;
> +};
kerneldoc the above would be helpful.
> +
> +static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
> +{
> + mxs_reset_block(i2c->regs);
> + __raw_writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
> +}
readl/writel are the usual way to use ioremaped() memory. If there's an
exception here, please document why.
> +static void mxs_i2c_pioq_setup_write(struct mxs_i2c_dev *i2c,
> + u8 addr, u8 *buf, int len, int flags)
> +{
> + u32 data;
> + int i, shifts_left;
> +
> + data = MXS_CMD_I2C_WRITE | MXS_I2C_CTRL0_XFER_COUNT(len + 1) | flags;
> + __raw_writel(data, i2c->regs + MXS_I2C_QUEUECMD);
> +
> + /* Start with address, then append buffer */
> + data = ((addr << 1) | I2C_SMBUS_WRITE) << 24;
> +
> + for (i = 0; i < len; i++) {
> + data >>= 8;
> + data |= buf[i] << 24;
> + if ((i & 3) == 2)
> + __raw_writel(data, i2c->regs + MXS_I2C_DATA);
> + }
> +
> + shifts_left = 24 - (i & 3) * 8;
> + if (shifts_left)
> + __raw_writel(data >> shifts_left, i2c->regs + MXS_I2C_DATA);
> +}
I'm going to have a think about the above, since it looks rather
hard to understand. Any chance of re-writing this?
> +static int mxs_i2c_wait_for_data(struct mxs_i2c_dev *i2c)
> +{
> + unsigned long timeout = jiffies + msecs_to_jiffies(1000);
> +
> + while (__raw_readl(i2c->regs + MXS_I2C_QUEUESTAT)
> + & MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY) {
> + if (time_after(jiffies, timeout))
> + return -ETIMEDOUT;
> + cond_resched();
> + }
> +
> + return 0;
> +}
surely there's a relevant wait_event here?
> +static int __devinit mxs_i2c_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct mxs_i2c_dev *i2c;
> + struct i2c_adapter *adap;
> + struct resource *res;
> + resource_size_t res_size;
> + int err, irq;
> +
> + i2c = devm_kzalloc(dev, sizeof(struct mxs_i2c_dev), GFP_KERNEL);
> + if (!i2c)
> + return -ENOMEM;
Possibly be worth printing an error.
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res)
> + return -ENODEV;
-ENODEV gets ignored by the platform bus probe.
> +
> + res_size = resource_size(res);
> + if (!devm_request_mem_region(dev, res->start, res_size, res->name))
> + return -EBUSY;
> +
> + i2c->regs = devm_ioremap_nocache(dev, res->start, res_size);
> + if (!i2c->regs)
> + return -EBUSY;
Maybe there should be a devm request to do all of the above in one go.
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0)
> + return irq;
> +
> + err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
> + if (err)
> + return err;
> +
> + i2c->dev = dev;
> + platform_set_drvdata(pdev, i2c);
> +
> + /* Do reset to enforce correct startup after pinmuxing */
> + mxs_i2c_reset(i2c);
> + __raw_writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
> + i2c->regs + MXS_I2C_QUEUECTRL_SET);
> +
> + adap = &i2c->adapter;
> + strncpy(adap->name, "MXS I2C adapter", sizeof(adap->name));
isn't there a version of this call that ensures proper termination
of the string if it is too long?
> +static struct platform_driver mxs_i2c_driver = {
> + .driver = {
> + .name = "mxs-i2c",
> + .owner = THIS_MODULE,
> + },
> + .remove = __devexit_p(mxs_i2c_remove),
> +};
> +
> +static int __init mxs_i2c_init(void)
> +{
> + return platform_driver_probe(&mxs_i2c_driver, mxs_i2c_probe);
> +}
> +subsys_initcall(mxs_i2c_init);
no assumption of hot plug platform devices?
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