[U-Boot] [PATCH v2 2/6] drivers/power/pmic: Add tps65217 driver

Tom Rini trini at ti.com
Wed Aug 28 15:16:00 CEST 2013 

On Wed, Aug 14, 2013 at 10:25:43PM +0200, Lukasz Majewski wrote:
> On Wed, 14 Aug 2013 11:57:06 -0400 Tom Rini <trini at ti.com> wrote:
> > On Wed, Aug 14, 2013 at 05:08:12PM +0200, Lukasz Majewski wrote:
> > > Hi Tom, Greg
> > >
> > > > From: Greg Guyotte <gguyotte at ti.com>
> > > >
> > > > Add a driver for the TPS65217 PMIC that is found in the Beaglebone
> > > > family of boards.
> > > >
> > > > Signed-off-by: Greg Guyotte <gguyotte at ti.com>
> > > > [trini: Split and rework Greg's changes into new drivers/power
> > > > framework]
> > > > Signed-off-by: Tom Rini <trini at ti.com>
> > > >
> > > > ---
> > > > Changes in v2:
> > > > - Address Dan's comments
> > > > - Change to SPDX license tag
> > > > - Add TRM link in the header
> > > >
> > > > Signed-off-by: Tom Rini <trini at ti.com>
> > > > ---
> > > >  drivers/power/pmic/Makefile        |    1 +
> > > >  drivers/power/pmic/pmic_tps65217.c |  109
> > > > ++++++++++++++++++++++++++++++++++++
> > > > include/power/tps65217.h           |   79
> > > > ++++++++++++++++++++++++++ 3 files changed, 189 insertions(+)
> > > > create mode 100644 drivers/power/pmic/pmic_tps65217.c create mode
> > > > 100644 include/power/tps65217.h
> > > >
> > > > diff --git a/drivers/power/pmic/Makefile
> > > > b/drivers/power/pmic/Makefile index f054470..ac2b625 100644
> > > > --- a/drivers/power/pmic/Makefile
> > > > +++ b/drivers/power/pmic/Makefile
> > > > @@ -13,6 +13,7 @@ COBJS-$(CONFIG_POWER_MAX8998) += pmic_max8998.o
> > > >  COBJS-$(CONFIG_POWER_MAX8997) += pmic_max8997.o
> > > >  COBJS-$(CONFIG_POWER_MUIC_MAX8997) += muic_max8997.o
> > > >  COBJS-$(CONFIG_POWER_MAX77686) += pmic_max77686.o
> > > > +COBJS-$(CONFIG_POWER_TPS65217) += pmic_tps65217.o
> > > >  
> > > >  COBJS := $(COBJS-y)
> > > >  SRCS := $(COBJS:.o=.c)
> > > > diff --git a/drivers/power/pmic/pmic_tps65217.c
> > > > b/drivers/power/pmic/pmic_tps65217.c new file mode 100644
> > > > index 0000000..36e9024
> > > > --- /dev/null
> > > > +++ b/drivers/power/pmic/pmic_tps65217.c
> > > > @@ -0,0 +1,109 @@
> > > > +/*
> > > > + * (C) Copyright 2011-2013
> > > > + * Texas Instruments, <www.ti.com>
> > > > + *
> > > > + * SPDX-License-Identifier: GPL-2.0+
> > > > + */
> > > > +
> > > > +#include <common.h>
> > > > +#include <i2c.h>
> > > > +#include <power/tps65217.h>
> > > > +
> > > > +/**
> > > > + * tps65217_reg_read() - Generic function that can read a
> > > > TPS65217 register
> > > > + * @src_reg: Source register address
> > > > + * @src_val: Address of destination variable
> > > > + * @return: 0 for success, not 0 on failure.
> > > > + */
> > > > +int tps65217_reg_read(uchar src_reg, uchar *src_val)
> > > > +{
> > > > + return i2c_read(TPS65217_CHIP_PM, src_reg, 1, src_val,
> > > > 1);
> > >
> > > Would it be possible to comply with pmic driver model?
> > > It can be found at ./drivers/power/power_core.c
> >
> > At the high level, not yet.  We don't have battery support (but fixing
> > that to be optional in the core wouldn't be hard) but the general pmic
> > code assumes one pmic charger per binary.
>
> As fair as I remember, there is no such assumption. The pmic driver
> allocates each pmic object separately (which can be distinguished by
> unique name - also many instances of the same devices are possible).
> Each power device is treated in the same way (described by struct
> pmic), no matter if it is a battery, charger, PMIC or MUIC.

Getting back to this thread again, sorry, drivers/power/pmic/pmic_max*
each has 'pmic_init' as a function meaning that only one each may be
built at a time.

> The tps65217_reg_read() method is used at board/ti/am335x/board.c -
> [PATCH v2 6/6] am335x_evm: am33xx_spl_board_init function and scale
> core frequency
>
> It is a similar use to pmic_init_max8997(void) defined
> at board/samsung/trats/trats.c

In concept, yes, except we might have either a tps65910 or a tps65217
and we won't know which until run-time, so we need to build in both.

> > We need both in the same
> > binary (since we decide at run-time if it's one of the boards with
> > 65910 or 65217).
>
> The pmic core can register both devices, then with OF decide to which
> one refer with e.g. p->name field.

Except for the function problem above, yes :)

> > > Moreover the generic function for reading/writing data to/from pmic
> > > is already defined at ./drivers/power/power_{i2c|spi}.c
> > >
> > > Maybe it would be possible to use/modify the already available code?
> >
> > Without the MAX family datasheets handy, I'm not sure how exactly the
> > tx_num stuff maps to the password concept the TI parts have.  Skimming
> > the kernel mfd drivers implies to me that logic ends up being per-chip
> > (or at least vendor).
>
> We have spent some time with Stefano to provide correct read/write for
> the following:
>
> - 1,2,3 bytes transfers
> - little + big endian data format support
> - support for SPI and I2C.
>
> This is already implemented at pmic_reg_write().

Right, but it won't buy us anything when we have to wrap our call around
that with calls to do the password logic.  That's actually the "hard"
part of these writes.

> > [snip]
> > > > +/**
> > > > + * tps65217_voltage_update() - Function to change a voltage
> > > > level, as this
> > > > + *       is a multi-step process.
> > > > + * @dc_cntrl_reg:       DC voltage control register to
> > > > change.
> > > > + * @volt_sel:       New value for the voltage
> > > > register
> > > > + * @return:       0 for success, not 0 on
> > > > failure.
> > > > + */
> > > > +int tps65217_voltage_update(uchar dc_cntrl_reg, uchar volt_sel)
> > >
> > > Maybe pmic_set_output() method from ./drivers/power/power_core.c
> > > can be reused?
> >
> > I'm not sure.
>
> At least we shall give it a try.

If we make pmic_reg_write be per-chip or so, yes, we could make use of a
general "do something" function.

> > [snip]
> > > > +#define TPS65217_SEQ6 0x1E
> > >
> > > Shouldn't the above registers be defined as enum?
> > >
> > > For example at ./include/power/max8997_pmic.h
> > > /* MAX 8997 registers */
> > > enum {
> > > MAX8997_REG_PMIC_ID0 = 0x00,
> > > MAX8997_REG_PMIC_ID1 = 0x01,
> > > MAX8997_REG_INTSRC = 0x02,
> > > ....
> > > PMIC_NUM_OF_REGS
> >
> > I assume it's a style thing I've overlooked, so sure, not a problem in
> > general.
> >
>
> Ok, thanks.
>
> I'm aware, that current pmic framework has some shortcomings, but I
> also believe that it can be developed to serve as a unified power
> management framework for u-boot users.

Right, but we need to think about it a bit more and the first step is
getting some non-Maxim chips in the area so people see them.  Then we
can adapt everyone as a follow-up.

-- 
Tom

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