Date:   Mon, 8 May 2017 10:00:05 +0200
From:   Peter Rosin <peda@...ntia.se>
To:     Philipp Zabel <p.zabel@...gutronix.de>
CC:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Sakari Ailus <sakari.ailus@....fi>,
        Steve Longerbeam <slongerbeam@...il.com>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <kernel@...gutronix.de>
Subject: Re: [RFC v3 2/2] mux: mmio-based syscon mux controller

Hi Philipp,

With the ack on the bindings in place, I'm going to pile these
two patches on top of my mux series when I send v15 next week (or
whenever v4.12-rc1 is out). There are a pair of nitpicks that I'm
going to fix myself, so no need for a resend.

Thank you very much for making use of the new code, I hope the
"3rd party interest" will help getting the mux series merged...

On 2017-04-28 13:52, Philipp Zabel wrote:
> This adds a driver for mmio-based syscon multiplexers controlled by
> bitfields in a syscon register range.
> 
> Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
> ---
> Changes since v2:
>  - Updated CONFIG description to multi-mux
>  - Use mux_control_get_index instead of open-coding it
>  - Read mux-reg-masks and idle-states values in a single loop using
>    individual read_u32_index calls instead of using read_u32_array
>  - Verify bitmask
> ---
>  drivers/mux/Kconfig    |  13 +++++
>  drivers/mux/Makefile   |   1 +
>  drivers/mux/mux-mmio.c | 140 +++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 154 insertions(+)
>  create mode 100644 drivers/mux/mux-mmio.c
> 
> diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
> index 34b8284d6d29e..50e7c5d557a05 100644
> --- a/drivers/mux/Kconfig
> +++ b/drivers/mux/Kconfig
> @@ -43,4 +43,17 @@ config MUX_GPIO
>  	  To compile the driver as a module, choose M here: the module will
>  	  be called mux-gpio.
>  
> +config MUX_MMIO
> +	tristate "MMIO register bitfield-controlled Multiplexer"
> +	depends on OF && MFD_SYSCON

Enable building when COMPILE_TEST is selected:
	depends on (OF && MFD_SYSCON) || COMPILE_TEST

(also adding that to the other drivers in the mux series)

> +	help
> +	  MMIO register bitfield-controlled Multiplexer controller.
> +
> +	  The driver builds multiplexer controllers for bitfields in a syscon
> +	  register. For N bit wide bitfields, there will be 2^N possible
> +	  multiplexer states.
> +
> +	  To compile the driver as a module, choose M here: the module will
> +	  be called mux-mmio.
> +
>  endif
> diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
> index b00a7d37d2fbe..6bac5b0fea137 100644
> --- a/drivers/mux/Makefile
> +++ b/drivers/mux/Makefile
> @@ -5,3 +5,4 @@
>  obj-$(CONFIG_MULTIPLEXER)	+= mux-core.o
>  obj-$(CONFIG_MUX_ADG792A)	+= mux-adg792a.o
>  obj-$(CONFIG_MUX_GPIO)		+= mux-gpio.o
> +obj-$(CONFIG_MUX_MMIO)		+= mux-mmio.o
> diff --git a/drivers/mux/mux-mmio.c b/drivers/mux/mux-mmio.c
> new file mode 100644
> index 0000000000000..d2477d62d6eed
> --- /dev/null
> +++ b/drivers/mux/mux-mmio.c
> @@ -0,0 +1,140 @@
> +/*
> + * MMIO register bitfield-controlled multiplexer driver
> + *
> + * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@...gutronix.de>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/err.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/mux/driver.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +
> +static int mux_mmio_set(struct mux_control *mux, int state)
> +{
> +	struct regmap_field **fields = mux_chip_priv(mux->chip);
> +
> +	return regmap_field_write(fields[mux_control_get_index(mux)], state);
> +}
> +
> +static const struct mux_control_ops mux_mmio_ops = {
> +	.set = mux_mmio_set,
> +};
> +
> +static const struct of_device_id mux_mmio_dt_ids[] = {
> +	{ .compatible = "mmio-mux", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
> +
> +static int mux_mmio_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct regmap_field **fields;
> +	struct mux_chip *mux_chip;
> +	struct regmap *regmap;
> +	int num_fields;
> +	int ret;
> +	int i;
> +
> +	regmap = syscon_node_to_regmap(np->parent);
> +	if (IS_ERR(regmap)) {
> +		ret = PTR_ERR(regmap);
> +		dev_err(dev, "failed to get regmap: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = of_property_count_u32_elems(np, "mux-reg-masks");
> +	if (ret == 0 || ret % 2)
> +		ret = -EINVAL;
> +	if (ret < 0) {
> +		dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
> +			ret);
> +		return ret;
> +	}
> +	num_fields = ret / 2;
> +
> +	mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
> +				       sizeof(*fields));
> +	if (IS_ERR(mux_chip))
> +		return PTR_ERR(mux_chip);
> +
> +	fields = mux_chip_priv(mux_chip);
> +
> +	for (i = 0; i < num_fields; i++) {
> +		struct mux_control *mux = &mux_chip->mux[i];
> +		struct reg_field field;
> +		s32 idle_state = MUX_IDLE_AS_IS;
> +		u32 reg, mask;
> +		int bits;
> +
> +		ret = of_property_read_u32_index(np, "mux-reg-masks",
> +						 2 * i, &reg);
> +		if (!ret)
> +			ret = of_property_read_u32_index(np, "mux-reg-masks",
> +							 2 * i + 1, &mask);
> +		if (ret < 0) {
> +			dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
> +				i, ret);
> +			return ret;
> +		}
> +
> +		field.reg = reg;
> +		field.msb = fls(mask) - 1;
> +		field.lsb = ffs(mask) - 1;
> +
> +		if (mask != GENMASK(field.msb, field.lsb)) {
> +			dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
> +				i, mask);
> +			return -EINVAL;
> +		}
> +
> +		fields[i] = devm_regmap_field_alloc(dev, regmap, field);
> +		if (IS_ERR(fields[i])) {
> +			ret = PTR_ERR(fields[i]);
> +			dev_err(dev, "bitfield %d: failed allocate: %d\n",
> +				i, ret);
> +			return ret;
> +		}
> +
> +		bits = 1 + field.msb - field.lsb;
> +		mux->states = 1 << bits;
> +
> +		of_property_read_u32_index(np, "idle-states", i, &idle_state);

Adding a (u32 *) cast here, in order to silence sparse.

drivers/mux/mux-mmio.c:112:67: warning: incorrect type in argument 4 (different signedness)
drivers/mux/mux-mmio.c:112:67:    expected unsigned int [usertype] *out_value
drivers/mux/mux-mmio.c:112:67:    got signed int *<noident>

Cheers,
peda

> +		if (idle_state != MUX_IDLE_AS_IS) {
> +			if (idle_state < 0 || idle_state >= mux->states) {
> +				dev_err(dev, "bitfield: %d: out of range idle state %d\n",
> +					i, idle_state);
> +				return -EINVAL;
> +			}
> +
> +			mux->idle_state = idle_state;
> +		}
> +	}
> +
> +	mux_chip->ops = &mux_mmio_ops;
> +
> +	return devm_mux_chip_register(dev, mux_chip);
> +}
> +
> +static struct platform_driver mux_mmio_driver = {
> +	.driver = {
> +		.name = "mmio-mux",
> +		.of_match_table	= of_match_ptr(mux_mmio_dt_ids),
> +	},
> +	.probe = mux_mmio_probe,
> +};
> +module_platform_driver(mux_mmio_driver);
> +
> +MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
> +MODULE_AUTHOR("Philipp Zabel <p.zabel@...gutronix.de>");
> +MODULE_LICENSE("GPL v2");
> 

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