RE: [PATCH] drivers: mux: Generic register bitfield-based multiplexer driver

From: Leo Li
Date: Mon Feb 18 2019 - 16:07:24 EST

Next message: Sowjanya Komatineni: "[PATCH V2] i2c: tegra: fix tegra186 hw feature support for has_mst_fifo_reg"
Previous message: Tejun Heo: "Re: [PATCH] doc: cgroup: correct the wrong information about measure of memory pressure"
In reply to: Peter Rosin: "Re: [PATCH] drivers: mux: Generic register bitfield-based multiplexer driver"
Next in thread: Peter Rosin: "Re: [PATCH] drivers: mux: Generic register bitfield-based multiplexer driver"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

> -----Original Message-----
> From: Peter Rosin <peda@xxxxxxxxxx>
> Sent: Monday, February 18, 2019 8:28 AM
> To: Pankaj Bansal <pankaj.bansal@xxxxxxx>; Leo Li <leoyang.li@xxxxxxx>;
> linux-kernel@xxxxxxxxxxxxxxx; Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> Subject: Re: [PATCH] drivers: mux: Generic register bitfield-based
> multiplexer driver
>
> On 2019-02-18 11:20, Pankaj Bansal wrote:
> > Hi Peter,
> >
> >> -----Original Message-----
> >> From: Peter Rosin [mailto:peda@xxxxxxxxxx]
> >> Sent: Monday, 18 February, 2019 03:17 PM
> >> To: Pankaj Bansal <pankaj.bansal@xxxxxxx>; Leo Li
> >> <leoyang.li@xxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; Philipp Zabel
> >> <p.zabel@xxxxxxxxxxxxxx>
> >> Subject: Re: [PATCH] drivers: mux: Generic register bitfield-based
> >> multiplexer driver
> >>
> >> Hi!
> >>
> >> On 2019-02-18 06:40, Pankaj Bansal wrote:
> >>> Generic register bitfield-based multiplexer driver that controls the
> >>> multiplexer producer defined under a parent node.
> >>> The driver corresponding to parent node provides register read/write
> >>> capabilities.
> >>
> >> This driver is just a rename of drivers/mux/mmio.c with a one-liner
> >> on top. And there's a license change too. That's obnoxious. Please
> >> keep this as GPL v2. Not that I /think/ Philipp nor Pengutronix cares
> deeply, but what do I know?
> >> Changing the license as you copy the code is simply not all right.
> >
> > My Apologies. I will fix it as I send V2.
> >
> >>
> >> Anyway, I would prefer if you could extend drivers/mux/mmio.c to
> >> support both compatibles, and using the compatible to select if
> >>
> >> regmap = syscon_node_to_regmap(np->parent);
> >>
> >> or
> >>
> >> regmap = dev_get_regmap(dev->parent, NULL);
> >>
> >> is called to get to the desired regmap.
> >
> > This can be done. The name mmio.c however suggests that mux is
> controlled by a Memory mapped device.
> > IMO, if the generic regmap API is to be added to it, the name needs to
> changed. Any suggestions ?
>
> Just keep the driver name as is, there is no shortage of drivers supporting
> more than one thing...

You are right that a lot of drivers support multiple functions. But the problem here is that the current name mmio is only a subset of what the updated driver will handle, which can create confusion.

Regards,
Leo
>
> Cheers,
> Peter
>
> >>
> >> Philipp, you don't object to extending the mmio driver, right?
> >>
> >> Or are there more differences that I failed to notice?
> >
> > Nope, it's the only difference.
> >
> >>
> >> Cheers,
> >> Peter
> >>
> >>>
> >>> Signed-off-by: Pankaj Bansal <pankaj.bansal@xxxxxxx>
> >>> ---
> >>>
> >>> Notes:
> >>> Dependencies:
> >>> -
> >>>
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fp
> >>> at
> >>>
> >>
> chwork.ozlabs.org%2Fpatch%2F1043790%2F&data=02%7C01%7Cpankaj.
> b
> >> ansa
> >>>
> >>
> l%40nxp.com%7C3b8a1e8520ce4345105108d695861210%7C686ea1d3bc2b4c6
> f
> >> a92cd
> >>>
> >>
> 99c5c301635%7C0%7C0%7C636860800396857042&sdata=5e%2BhyasYwf
> >> uc%2Fbr
> >>> 1u6WKlKybYipz5c4ndBeLZDflHqk%3D&reserved=0
> >>>
> >>> drivers/mux/Kconfig | 13 ++++
> >>> drivers/mux/Makefile | 2 +
> >>> drivers/mux/regmap.c | 139
> >> +++++++++++++++++++++++++++++++++++++++++
> >>> 3 files changed, 154 insertions(+)
> >>>
> >>> diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig index
> >>> 7659d6c5f718..a412d0955258 100644
> >>> --- a/drivers/mux/Kconfig
> >>> +++ b/drivers/mux/Kconfig
> >>> @@ -58,4 +58,17 @@ config MUX_MMIO
> >>> To compile the driver as a module, choose M here: the module will
> >>> be called mux-mmio.
> >>>
> >>> +config MUX_REGMAP
> >>> + tristate "Regmap register bitfield-controlled Multiplexer"
> >>> + depends on (OF && REGMAP) || COMPILE_TEST
> >>> + help
> >>> + Regmap register bitfield-controlled Multiplexer controller.
> >>> +
> >>> + The driver builds multiplexer controllers for bitfields in a regmap
> >>> + device 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 regmap-mmio.
> >>> +
> >>> endmenu
> >>> diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile index
> >>> 6e9fa47daf56..ae1bafac0cbd 100644
> >>> --- a/drivers/mux/Makefile
> >>> +++ b/drivers/mux/Makefile
> >>> @@ -8,9 +8,11 @@ mux-adg792a-objs := adg792a.o
> >>> mux-adgs1408-objs := adgs1408.o
> >>> mux-gpio-objs := gpio.o
> >>> mux-mmio-objs := mmio.o
> >>> +mux-regmap-objs := regmap.o
> >>>
> >>> obj-$(CONFIG_MULTIPLEXER) += mux-core.o
> >>> obj-$(CONFIG_MUX_ADG792A) += mux-adg792a.o
> >>> obj-$(CONFIG_MUX_ADGS1408) += mux-adgs1408.o
> >>> obj-$(CONFIG_MUX_GPIO) += mux-gpio.o
> >>> obj-$(CONFIG_MUX_MMIO) += mux-mmio.o
> >>> +obj-$(CONFIG_MUX_REGMAP) += mux-regmap.o
> >>> diff --git a/drivers/mux/regmap.c b/drivers/mux/regmap.c new file
> >>> mode
> >>> 100644 index 000000000000..c2156302929a
> >>> --- /dev/null
> >>> +++ b/drivers/mux/regmap.c
> >>> @@ -0,0 +1,139 @@
> >>> +// SPDX-License-Identifier: GPL-2.0+
> >>> +/*
> >>> + * Regmap register bitfield-controlled multiplexer driver
> >>> + *
> >>> + * Based on drivers/mux/mmio.c
> >>> + *
> >>> + * Copyright 2019 NXP
> >>> + */
> >>> +
> >>> +#include <linux/bitops.h>
> >>> +#include <linux/err.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_regmap_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_regmap_ops = {
> >>> + .set = mux_regmap_set,
> >>> +};
> >>> +
> >>> +static const struct of_device_id mux_regmap_dt_ids[] = {
> >>> + { .compatible = "reg-mux", },
> >>> + { /* sentinel */ }
> >>> +};
> >>> +MODULE_DEVICE_TABLE(of, mux_regmap_dt_ids);
> >>> +
> >>> +static int mux_regmap_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 = dev_get_regmap(dev->parent, NULL);
> >>> + 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,
> >>> + (u32 *)&idle_state);
> >>> + 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_regmap_ops;
> >>> +
> >>> + return devm_mux_chip_register(dev, mux_chip); }
> >>> +
> >>> +static struct platform_driver mux_regmap_driver = {
> >>> + .driver = {
> >>> + .name = "regmap-mux",
> >>> + .of_match_table =
> of_match_ptr(mux_regmap_dt_ids),
> >>> + },
> >>> + .probe = mux_regmap_probe,
> >>> +};
> >>> +module_platform_driver(mux_regmap_driver);
> >>> +
> >>> +MODULE_DESCRIPTION("Regmap register bitfield-controlled
> multiplexer
> >>> +driver"); MODULE_AUTHOR("Pankaj Bansal
> <pankaj.bansal@xxxxxxx>");
> >>> +MODULE_LICENSE("GPL");
> >>>
> >

Next message: Sowjanya Komatineni: "[PATCH V2] i2c: tegra: fix tegra186 hw feature support for has_mst_fifo_reg"
Previous message: Tejun Heo: "Re: [PATCH] doc: cgroup: correct the wrong information about measure of memory pressure"
In reply to: Peter Rosin: "Re: [PATCH] drivers: mux: Generic register bitfield-based multiplexer driver"
Next in thread: Peter Rosin: "Re: [PATCH] drivers: mux: Generic register bitfield-based multiplexer driver"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]