Date:	Tue, 18 Nov 2014 17:21:56 +0000
From:	Lee Jones <lee.jones@...aro.org>
To:	Raymond Tan <raymond.tan@...el.com>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>, linux-kernel@...r.kernel.org,
	Alvin Chen <alvin.chen@...el.com>,
	Andriy Shevchenko <andriy.shevchenko@...el.com>
Subject: Re: [PATCH v2 1/1] mfd: intel_quark_i2c_gpio: Add Intel Quark X1000
 I2C-GPIO MFD Driver

On Tue, 11 Nov 2014, Raymond Tan wrote:

> In Quark X1000, there's a single PCI device that provides both
> an I2C controller and a GPIO controller. This MFD driver will
> split the 2 devices for their respective drivers.
> 
> This patch is based on Josef Ahmad's initial work for Quark enabling.
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Weike Chen <alvin.chen@...el.com>
> Signed-off-by: Raymond Tan <raymond.tan@...el.com>
> ---
>  drivers/mfd/Kconfig                |   11 ++
>  drivers/mfd/Makefile               |    1 +
>  drivers/mfd/intel_quark_i2c_gpio.c |  298 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 310 insertions(+)
>  create mode 100644 drivers/mfd/intel_quark_i2c_gpio.c
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index b7c74a7..d01d042 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -219,6 +219,17 @@ config HTC_I2CPLD
>  	  This device provides input and output GPIOs through an I2C
>  	  interface to one or more sub-chips.
>  
> +config MFD_INTEL_QUARK_I2C_GPIO
> +	tristate "Intel Quark MFD I2C GPIO"
> +	depends on PCI && X86

Why have you bunched these two up?

> +	depends on COMMON_CLK

I don't think you should depend on this.  Just use the API and fail if
it doesn't find the clock you're after.

> +	select MFD_CORE
> +	help
> +	  This MFD provides support for I2C and GPIO that exist only
> +	  in a single PCI device. It splits the 2 IO devices to
> +	  their respective IO driver.
> +	  The GPIO exports a total amount of 8 interrupt-capable GPIOs.
> +
>  config LPC_ICH
>  	tristate "Intel ICH LPC"
>  	depends on PCI
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 8a28dc9..d42652d 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -133,6 +133,7 @@ obj-$(CONFIG_AB8500_CORE)	+= ab8500-core.o ab8500-sysctrl.o
>  obj-$(CONFIG_MFD_TIMBERDALE)    += timberdale.o
>  obj-$(CONFIG_PMIC_ADP5520)	+= adp5520.o
>  obj-$(CONFIG_MFD_KEMPLD)	+= kempld-core.o
> +obj-$(CONFIG_MFD_INTEL_QUARK_I2C_GPIO)	+= intel_quark_i2c_gpio.o
>  obj-$(CONFIG_LPC_SCH)		+= lpc_sch.o
>  obj-$(CONFIG_LPC_ICH)		+= lpc_ich.o
>  obj-$(CONFIG_MFD_RDC321X)	+= rdc321x-southbridge.o
> diff --git a/drivers/mfd/intel_quark_i2c_gpio.c b/drivers/mfd/intel_quark_i2c_gpio.c
> new file mode 100644
> index 0000000..eed95da
> --- /dev/null
> +++ b/drivers/mfd/intel_quark_i2c_gpio.c
> @@ -0,0 +1,298 @@
> +/*
> + * Intel Quark MFD PCI driver for I2C & GPIO
> + *
> + * Copyright(c) 2014 Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * Intel Quark PCI device for I2C and GPIO controller sharing the same
> + * PCI function. This PCI driver will split the 2 devices into their
> + * respective drivers.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/mfd/core.h>
> +#include <linux/clkdev.h>
> +#include <linux/clk-provider.h>
> +#include <linux/dmi.h>
> +#include <linux/platform_data/gpio-dwapb.h>
> +#include <linux/platform_data/i2c-designware.h>
> +
> +/* PCI BAR for register base address */
> +#define MFD_I2C_BAR		0
> +#define MFD_GPIO_BAR		1
> +
> +/* The base GPIO number under GPIOLIB framework */
> +#define INTEL_QUARK_MFD_GPIO_BASE	8
> +
> +/* The default number of South-Cluster GPIO on Quark. */
> +#define INTEL_QUARK_MFD_NGPIO		8
> +
> +/* The DesignWare GPIO ports on Quark. */
> +#define INTEL_QUARK_GPIO_NPORTS	1
> +
> +#define INTEL_QUARK_IORES_MEM	0
> +#define INTEL_QUARK_IORES_IRQ	1
> +
> +#define INTEL_QUARK_I2C_CONTROLLER_CLK "i2c_designware.0"
> +
> +/* The Quark I2C controller source clock */
> +#define INTEL_QUARK_I2C_CLK_HZ	33000000
> +
> +#define INTEL_QUARK_I2C_NCLK	1
> +
> +struct clk *intel_quark_i2c_clk;
> +struct clk_lookup *intel_quark_i2c_clk_lookups;

Why do these need to be global?

> +struct i2c_mode_info {
> +	const char *name;
> +	unsigned int i2c_scl_freq;
> +};
> +
> +static const struct i2c_mode_info platform_i2c_mode_info[] = {
> +	{
> +		.name = "Galileo",
> +		.i2c_scl_freq = 100000,
> +	},
> +	{
> +		.name = "GalileoGen2",
> +		.i2c_scl_freq = 400000,
> +	},
> +};
> +
> +static struct resource intel_quark_i2c_res[] = {
> +	[INTEL_QUARK_IORES_MEM] = {
> +		.flags = IORESOURCE_MEM,
> +	},
> +	[INTEL_QUARK_IORES_IRQ] = {
> +		.flags = IORESOURCE_IRQ,
> +	},
> +};
> +
> +static struct resource intel_quark_gpio_res[] = {
> +	[INTEL_QUARK_IORES_MEM] = {
> +		.flags = IORESOURCE_MEM,
> +	},
> +};
> +
> +static struct mfd_cell intel_quark_mfd_cells[] = {
> +	{
> +		.id = MFD_I2C_BAR,
> +		.name = "i2c_designware",
> +		.num_resources = ARRAY_SIZE(intel_quark_i2c_res),
> +		.resources = intel_quark_i2c_res,
> +		.ignore_resource_conflicts = true,
> +	},
> +	{
> +		.id = MFD_GPIO_BAR,
> +		.name = "gpio-dwapb",
> +		.num_resources = ARRAY_SIZE(intel_quark_gpio_res),
> +		.resources = intel_quark_gpio_res,
> +		.ignore_resource_conflicts = true,
> +	},
> +};
> +
> +static const struct pci_device_id intel_quark_mfd_ids[] = {
> +	{ PCI_VDEVICE(INTEL, 0x0934), },
> +	{ 0,}
> +};
> +MODULE_DEVICE_TABLE(pci, intel_quark_mfd_ids);
> +
> +static struct dwapb_platform_data *
> +intel_quark_prepare_pdata(struct pci_dev *pdev)
> +{
> +	struct dwapb_platform_data *pdata;
> +	struct device *dev = &pdev->dev;
> +
> +	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> +	if (!pdata)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* For intel quark x1000, it has only one port: portA */
> +	pdata->nports = INTEL_QUARK_GPIO_NPORTS;
> +	pdata->properties = devm_kcalloc(dev, pdata->nports,
> +					 sizeof(*pdata->properties),
> +					 GFP_KERNEL);
> +	if (!pdata->properties)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Set the properties for portA */
> +	pdata->properties->node	= NULL;
> +	pdata->properties->name	= "intel-quark-x1000-gpio-portA";
> +	pdata->properties->idx	= 0;
> +	pdata->properties->ngpio	= INTEL_QUARK_MFD_NGPIO;
> +	pdata->properties->gpio_base	= INTEL_QUARK_MFD_GPIO_BASE;
> +	pdata->properties->irq	= pdev->irq;
> +	pdata->properties->irq_shared	= true;
> +
> +	return pdata;
> +}
> +
> +static struct dw_i2c_platform_data *
> +intel_quark_get_i2c_mode(struct pci_dev *pdev)
> +{
> +	const char *board_name = dmi_get_system_info(DMI_BOARD_NAME);
> +	struct dw_i2c_platform_data *pdata;
> +	struct device *dev = &pdev->dev;
> +	unsigned int i;
> +
> +	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> +	if (!pdata)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Fast mode by default */
> +	pdata->i2c_scl_freq = 400000;
> +
> +	for (i = 0; i < ARRAY_SIZE(platform_i2c_mode_info); i++)
> +		if (!strcmp(board_name, platform_i2c_mode_info[i].name))
> +			pdata->i2c_scl_freq
> +				= platform_i2c_mode_info[i].i2c_scl_freq;
> +
> +	return pdata;
> +}

If this function going to be invoked from anywhere else?  If not, I
would suggest putting the content directly into
intel_quark_i2c_setup() to simplify things a little.

> +static int intel_quark_register_i2c_clk(struct pci_dev *pdev)
> +{
> +	intel_quark_i2c_clk_lookups = devm_kcalloc(

I suggest putting this into a device container (struct) and
simplifying the name, allot.

> +		&pdev->dev, INTEL_QUARK_I2C_NCLK,
> +		sizeof(*intel_quark_i2c_clk_lookups), GFP_KERNEL);
> +
> +	if (!intel_quark_i2c_clk_lookups)
> +		return -ENOMEM;
> +
> +	intel_quark_i2c_clk_lookups[0].dev_id = INTEL_QUARK_I2C_CONTROLLER_CLK;
> +
> +	intel_quark_i2c_clk = clk_register_fixed_rate(
> +		&pdev->dev, INTEL_QUARK_I2C_CONTROLLER_CLK, NULL,
> +		CLK_IS_ROOT, INTEL_QUARK_I2C_CLK_HZ);
> +
> +	return clk_register_clkdevs(intel_quark_i2c_clk,
> +		intel_quark_i2c_clk_lookups, INTEL_QUARK_I2C_NCLK);

We don't normally register clks from MFD.  Normally they are
registered in drivers/clk and fetched when a device requires them.
Why is this different?

> +}
> +
> +static void intel_quark_unregister_i2c_clk(void)
> +{
> +	if (!intel_quark_i2c_clk || !intel_quark_i2c_clk_lookups)
> +		return;
> +
> +	clkdev_drop(intel_quark_i2c_clk_lookups);
> +	clk_unregister(intel_quark_i2c_clk);
> +}
> +
> +static int intel_quark_i2c_setup(struct pci_dev *pdev, struct mfd_cell *cell)
> +{
> +	struct dw_i2c_platform_data *pdata;
> +	struct resource *res = (struct resource *)cell->resources;
> +	int retval;
> +
> +	res[INTEL_QUARK_IORES_MEM].start =
> +		pci_resource_start(pdev, MFD_I2C_BAR);
> +	res[INTEL_QUARK_IORES_MEM].end =
> +		pci_resource_end(pdev, MFD_I2C_BAR);
> +
> +	res[INTEL_QUARK_IORES_IRQ].start = pdev->irq;
> +	res[INTEL_QUARK_IORES_IRQ].end = pdev->irq;
> +
> +	retval = intel_quark_register_i2c_clk(pdev);
> +	if (retval) {
> +		dev_err(&pdev->dev, "Fixed clk register failed: %d\n", retval);
> +		return retval;
> +	}
> +
> +	pdata = intel_quark_get_i2c_mode(pdev);
> +	if (IS_ERR(pdata))
> +		return PTR_ERR(pdata);

Bring this functionality into here?

> +	cell->platform_data = pdata;
> +	cell->pdata_size = sizeof(*pdata);
> +
> +	return 0;
> +}
> +
> +static int intel_quark_gpio_setup(struct pci_dev *pdev, struct mfd_cell *cell)
> +{
> +	struct dwapb_platform_data *pdata;
> +	struct resource *res = (struct resource *)cell->resources;
> +
> +	res[INTEL_QUARK_IORES_MEM].start =
> +		pci_resource_start(pdev, MFD_GPIO_BAR);
> +	res[INTEL_QUARK_IORES_MEM].end =
> +		pci_resource_end(pdev, MFD_GPIO_BAR);
> +
> +	pdata = intel_quark_prepare_pdata(pdev);
> +	if (IS_ERR(pdata))
> +		return PTR_ERR(pdata);
> +
> +	cell->platform_data = pdata;
> +	cell->pdata_size = sizeof(*pdata);
> +
> +	return 0;
> +}

The different ways in which you deal with platform_data in _gpio_setup
and _i2c_setup is confusing.  _prepare_pdata insinuates that it's a
generic method for creating platform data, but it's actually only used
for the GPIO device.  I'm sure you can find a way to standardise these
call paths.

Can you just allocate and populate pdata in the setup functions.
Making all sorts of unnecessary (i.e. only called once) extra calls
into oddly named functions is not helping the readability of this
driver.

> +struct intel_quark_mfd_dev {
> +	int (*setup)(struct pci_dev *pdev, struct mfd_cell *cell);
> +	struct mfd_cell *cell;
> +};
> +
> +static struct intel_quark_mfd_dev intel_quark_mfd_devs[] = {
> +	{
> +		.cell = &intel_quark_mfd_cells[MFD_I2C_BAR],
> +		.setup = intel_quark_i2c_setup,
> +	},
> +	{
> +		.cell = &intel_quark_mfd_cells[MFD_GPIO_BAR],
> +		.setup = intel_quark_gpio_setup,
> +	},
> +	{
> +		/* terminator */
> +	},

{} will do just fine.

> +};
> +
> +static int intel_quark_mfd_probe(struct pci_dev *pdev,
> +				 const struct pci_device_id *id)
> +{
> +	struct intel_quark_mfd_dev *mfd_dev;
> +	int retval;
> +
> +	retval = pcim_enable_device(pdev);
> +	if (retval)
> +		return retval;
> +
> +	for (mfd_dev = intel_quark_mfd_devs; mfd_dev->cell; mfd_dev++)
> +		if (mfd_dev->setup) {
> +			retval = mfd_dev->setup(pdev, mfd_dev->cell);
> +			if (retval)
> +				return retval;
> +		}

I don't see the benifit in doing this at all.  Just:

intel_quark_i2c_setup();
intel_quark_gpio_setup();


> +	return mfd_add_devices(&pdev->dev, 0, intel_quark_mfd_cells,
> +		ARRAY_SIZE(intel_quark_mfd_cells), NULL, 0, NULL);
> +}
> +
> +static void intel_quark_mfd_remove(struct pci_dev *pdev)
> +{
> +	intel_quark_unregister_i2c_clk();
> +	mfd_remove_devices(&pdev->dev);
> +}
> +
> +static struct pci_driver intel_quark_mfd_driver = {
> +	.name		= "intel_quark_mfd_i2c_gpio",
> +	.id_table	= intel_quark_mfd_ids,
> +	.probe		= intel_quark_mfd_probe,
> +	.remove		= intel_quark_mfd_remove,
> +};
> +
> +module_pci_driver(intel_quark_mfd_driver);
> +
> +MODULE_AUTHOR("Raymond Tan <raymond.tan@...el.com>");
> +MODULE_DESCRIPTION("Intel Quark MFD PCI driver for I2C & GPIO");
> +MODULE_LICENSE("GPL v2");

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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