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Message-ID: <CACRpkdYTCgXo8FeitEfRujeWdshnsR3Kn57cKUZsA3CsZ5Cnrw@mail.gmail.com>
Date: Mon, 28 Jan 2019 13:49:04 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
Baolin Wang <baolin.wang@...aro.org>
Cc: Matti Vaittinen <mazziesaccount@...il.com>,
heikki.haikola@...rohmeurope.com, mikko.mutanen@...rohmeurope.com,
Lee Jones <lee.jones@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Mark Brown <broonie@...nel.org>,
Greg KH <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Bartosz Golaszewski <bgolaszewski@...libre.com>,
Sebastian Reichel <sre@...nel.org>,
Liam Girdwood <lgirdwood@...il.com>,
Alessandro Zummo <a.zummo@...ertech.it>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Wim Van Sebroeck <wim@...ux-watchdog.org>,
Guenter Roeck <linux@...ck-us.net>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-clk <linux-clk@...r.kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
Linux PM list <linux-pm@...r.kernel.org>,
linux-rtc@...r.kernel.org,
LINUXWATCHDOG <linux-watchdog@...r.kernel.org>
Subject: Re: [RFC PATCH v2 09/10] power: supply: Initial support for ROHM
BD70528 PMIC charger block
Hi Matti!
Thanks for your patch.
We are going to have a problem with the power subsystem.
These charging drivers are growing wild. This is starting to get out
of hand, we need some more framework for properly handling charging
state machines the kernel. Not specifically your problem, but
when working on the driver try to keep generic support in mind.
On Fri, Jan 25, 2019 at 12:06 PM Matti Vaittinen
<matti.vaittinen@...rohmeurope.com> wrote:
> +#define CHG_STAT_SUSPEND 0x0
> +#define CHG_STAT_TRICKLE 0x1
> +#define CHG_STAT_FAST 0x3
> +#define CHG_STAT_TOPOFF 0xe
> +#define CHG_STAT_DONE 0xf
> +#define CHG_STAT_OTP_TRICKLE 0x10
> +#define CHG_STAT_OTP_FAST 0x11
> +#define CHG_STAT_OTP_DONE 0x12
> +#define CHG_STAT_TSD_TRICKLE 0x20
> +#define CHG_STAT_TSD_FAST 0x21
> +#define CHG_STAT_TSD_TOPOFF 0x22
> +#define CHG_STAT_BAT_ERR 0x7f
So what I am seeing is that these states are starting to turn up in more
and more drivers, so we really need to think about a central management
component for charging state machines. I do not think they are all
that different after all.
> +BD_ERR_IRQ_HND(BAT_OV_DET, "Battery overvoltage detected\n");
> +BD_ERR_IRQ_HND(DBAT_DET, "Dead battery detected\n");
> +BD_ERR_IRQ_HND(COLD_DET, "Battery cold\n");
> +BD_ERR_IRQ_HND(HOT_DET, "Battery hot\n");
> +BD_ERR_IRQ_HND(CHG_TSD, "Charger thermal shutdown\n");
> +BD_ERR_IRQ_HND(DCIN2_OV_DET, "DCIN2 overvoltage detected\n");
> +
> +BD_INFO_IRQ_HND(BAT_OV_RES, "Battery voltage back to normal\n");
> +BD_INFO_IRQ_HND(COLD_RES, "Battery temperature back to normal\n");
> +BD_INFO_IRQ_HND(HOT_RES, "Battery temperature back to normal\n");
> +BD_INFO_IRQ_HND(BAT_RMV, "Battery removed\n");
> +BD_INFO_IRQ_HND(BAT_DET, "Battery detected\n");
> +BD_INFO_IRQ_HND(DCIN2_OV_RES, "DCIN2 voltage back to normal\n");
> +BD_INFO_IRQ_HND(DCIN2_RMV, "DCIN2 removed\n");
> +BD_INFO_IRQ_HND(DCIN2_DET, "DCIN2 detected\n");
> +BD_INFO_IRQ_HND(DCIN1_RMV, "DCIN1 removed\n");
> +BD_INFO_IRQ_HND(DCIN1_DET, "DCIN1 detected\n");
So we have states and events, and these events form edges
between the states, right?
I am certain you must have a graphical picture of this state
machine somewhere, it seems to be how charging hardware people
do their thinking.
> +/*
> + * For BD70528 voltage/current limits we happily accept any value which
> + * belongs the range. We could check if value matching the selector is
> + * desired by computing the range min + (sel - sel_low) * range step - but
> + * I guess it is enough if we use voltage/current which is closest (below)
> + * the requested?
> + */
> +static int find_selector_for_value_low(struct linear_range *r, int selectors,
> + unsigned int val, unsigned int *sel,
> + bool *found)
> +{
> + int i;
> + int ret = -EINVAL;
> +
> + *found = false;
> + for (i = 0; i < selectors; i++) {
> + if (r[i].min <= val) {
> + if (r[i].min + r[i].step * r[i].vals >= val) {
> + *found = true;
> + *sel = r[i].low_sel + (val - r[i].min) /
> + r[i].step;
> + ret = 0;
> + break;
> + }
> + /*
> + * If the range max is smaller than requested
> + * we can set the max supported value from range
> + */
> + *sel = r[i].low_sel + r[i].vals;
> + ret = 0;
> + }
> + }
> + return ret;
> +}
If I'm not mistaken this is yet another instance of linear interpolation
from a table?
We really need to think about abstracting this. Last time this
duplication appeared I suggested adding linear interpolation
primitives to:
include/linux/fixp-arith.h
I don't know what others say though?
Yours,
Linus Walleij
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