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To: =?utf-8?q?S=C3=B6ren_Brinkmann?= <soren.brinkmann@xilinx.com>,
        Rob Herring <rob.herring@calxeda.com>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Stephen Warren <swarren@wwwdotorg.org>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Rob Landley <rob@landley.net>, Grant Likely <grant.likely@linaro.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
        Joe Perches <joe@perches.com>
From: Mike Turquette <mturquette@linaro.org>
In-Reply-To: <b625092b-682c-4072-85a6-9f9d7f378ec0@VA3EHSMHS043.ehs.local>
Cc: <devicetree@vger.kernel.org>, <linux-doc@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>,
        Hyun Kwon <hyunk@xilinx.com>
References: <1379806839-13762-1-git-send-email-soren.brinkmann@xilinx.com>
 <b625092b-682c-4072-85a6-9f9d7f378ec0@VA3EHSMHS043.ehs.local>
Message-ID: <20131002231751.4343.81234@quantum>
User-Agent: alot/0.3.4
Subject: Re: [PATCH v5] clk: si570: Add a driver for SI570 oscillators
Date: Wed, 02 Oct 2013 16:17:51 -0700
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 25296
Lines: 692

Quoting Sören Brinkmann (2013-10-02 10:20:38)
> Hi Mike,
> 
> could you please comment on this/apply it to clk-next?

It looks good and is in the queue. Will show up in clk-next in a few
days.

Thanks,
Mike

> 
>         Thanks,
>         Sören
> 
> On Sat, Sep 21, 2013 at 04:40:39PM -0700, Soren Brinkmann wrote:
> > Add a driver for SILabs 570, 571, 598, 599 programmable oscillators.
> > The devices generate low-jitter clock signals and are reprogrammable via
> > an I2C interface.
> > 
> > Cc: Guenter Roeck <linux@roeck-us.net>
> > Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
> > ---
> > v5:
> >  - fix typo in bindings documentation
> >  - mention the unit for the 'temperature-stability' property
> >  - remove calls to clk_unregister() (the device managed code takes care
> >    of it)
> > 
> > v4:
> >  - actually check and handle error on clk_set_rate() call
> > 
> > v3:
> >  - add delay in the path for small frequency changes, which can take up
> >    to 100us according to the data sheet
> >  - use real range for usleep_range() argument
> >  - use dev_err() over dev_warn() in set_rate()
> >  - add list of applicable devices for 7ppm DT prop
> >  - remove comments regarding platform data
> >  - ignore 7ppm DT prop for incompatible devices
> >  - replace raw numbers with #defines
> >  - convert DT prop 'temperature-stability' from boolean to u32
> >  - make 'temperature-stability' DT prop required (actually not fully
> >    true, for 59x it is ignored and the driver does not require its
> >    presence)
> > 
> > v2:
> >  - document clock-output-names in bindings documentation
> >  - don't use wildcards in compatibility string
> >  - change Kconfig entry to "... 570 and compatible devices"
> >  - change some indentation flaws
> >  - use 10000 as MIN and MAX value in usleep_range
> >  - fail probe() if 'factory-fout' is not provided in DT
> >    - default factory fout #defines removed
> >  - use i2c driver_data instead of OF data
> >    - remove some related structs and data
> >  - rename DT property 'initial-fout' => 'clock-frequency' (like si5351
> >    driver)
> >  - add some more details regarding the 'factory-fout' DT property
> > ---
> >  .../devicetree/bindings/clock/silabs,si570.txt     |  39 ++
> >  drivers/clk/Kconfig                                |  10 +
> >  drivers/clk/Makefile                               |   1 +
> >  drivers/clk/clk-si570.c                            | 531 +++++++++++++++++++++
> >  4 files changed, 581 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/clock/silabs,si570.txt
> >  create mode 100644 drivers/clk/clk-si570.c
> > 
> > diff --git a/Documentation/devicetree/bindings/clock/silabs,si570.txt b/Documentation/devicetree/bindings/clock/silabs,si570.txt
> > new file mode 100644
> > index 0000000..c09f21e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/clock/silabs,si570.txt
> > @@ -0,0 +1,39 @@
> > +Binding for Silicon Labs 570, 571, 598 and 599 programmable
> > +I2C clock generators.
> > +
> > +Reference
> > +This binding uses the common clock binding[1]. Details about the devices can be
> > +found in the data sheets[2][3].
> > +
> > +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> > +[2] Si570/571 Data Sheet
> > +    http://www.silabs.com/Support%20Documents/TechnicalDocs/si570.pdf
> > +[3] Si598/599 Data Sheet
> > +    http://www.silabs.com/Support%20Documents/TechnicalDocs/si598-99.pdf
> > +
> > +Required properties:
> > + - compatible: Shall be one of "silabs,si570", "silabs,si571",
> > +                            "silabs,si598", "silabs,si599"
> > + - reg: I2C device address.
> > + - #clock-cells: From common clock bindings: Shall be 0.
> > + - factory-fout: Factory set default frequency. This frequency is part specific.
> > +              The correct frequency for the part used has to be provided in
> > +              order to generate the correct output frequencies. For more
> > +              details, please refer to the data sheet.
> > + - temperature-stability: Temperature stability of the device in PPM. Should be
> > +                       one of: 7, 20, 50 or 100.
> > +
> > +Optional properties:
> > + - clock-output-names: From common clock bindings. Recommended to be "si570".
> > + - clock-frequency: Output frequency to generate. This defines the output
> > +                 frequency set during boot. It can be reprogrammed during
> > +                 runtime through the common clock framework.
> > +
> > +Example:
> > +     si570: clock-generator@5d {
> > +             #clock-cells = <0>;
> > +             compatible = "silabs,si570";
> > +             temperature-stability = <50>;
> > +             reg = <0x5d>;
> > +             factory-fout = <156250000>;
> > +     };
> > diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> > index 279407a..349b88a 100644
> > --- a/drivers/clk/Kconfig
> > +++ b/drivers/clk/Kconfig
> > @@ -64,6 +64,16 @@ config COMMON_CLK_SI5351
> >         This driver supports Silicon Labs 5351A/B/C programmable clock
> >         generators.
> >  
> > +config COMMON_CLK_SI570
> > +     tristate "Clock driver for SiLabs 570 and compatible devices"
> > +     depends on I2C
> > +     depends on OF
> > +     select REGMAP_I2C
> > +     help
> > +     ---help---
> > +       This driver supports Silicon Labs 570/571/598/599 programmable
> > +       clock generators.
> > +
> >  config COMMON_CLK_S2MPS11
> >       tristate "Clock driver for S2MPS11 MFD"
> >       depends on MFD_SEC_CORE
> > diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> > index 7b11106..c0e94b3 100644
> > --- a/drivers/clk/Makefile
> > +++ b/drivers/clk/Makefile
> > @@ -40,6 +40,7 @@ obj-$(CONFIG_COMMON_CLK_AXI_CLKGEN) += clk-axi-clkgen.o
> >  obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
> >  obj-$(CONFIG_COMMON_CLK_MAX77686) += clk-max77686.o
> >  obj-$(CONFIG_COMMON_CLK_SI5351) += clk-si5351.o
> > +obj-$(CONFIG_COMMON_CLK_SI570) += clk-si570.o
> >  obj-$(CONFIG_COMMON_CLK_S2MPS11) += clk-s2mps11.o
> >  obj-$(CONFIG_CLK_TWL6040)    += clk-twl6040.o
> >  obj-$(CONFIG_CLK_PPC_CORENET)        += clk-ppc-corenet.o
> > diff --git a/drivers/clk/clk-si570.c b/drivers/clk/clk-si570.c
> > new file mode 100644
> > index 0000000..5d0ac9f
> > --- /dev/null
> > +++ b/drivers/clk/clk-si570.c
> > @@ -0,0 +1,531 @@
> > +/*
> > + * Driver for Silicon Labs Si570/Si571 Programmable XO/VCXO
> > + *
> > + * Copyright (C) 2010, 2011 Ericsson AB.
> > + * Copyright (C) 2011 Guenter Roeck.
> > + * Copyright (C) 2011 - 2013 Xilinx Inc.
> > + *
> > + * Author: Guenter Roeck <guenter.roeck@ericsson.com>
> > + *      Sören Brinkmann <soren.brinkmann@xilinx.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that 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.
> > + */
> > +
> > +#include <linux/clk-provider.h>
> > +#include <linux/delay.h>
> > +#include <linux/module.h>
> > +#include <linux/i2c.h>
> > +#include <linux/regmap.h>
> > +#include <linux/slab.h>
> > +
> > +/* Si570 registers */
> > +#define SI570_REG_HS_N1              7
> > +#define SI570_REG_N1_RFREQ0  8
> > +#define SI570_REG_RFREQ1     9
> > +#define SI570_REG_RFREQ2     10
> > +#define SI570_REG_RFREQ3     11
> > +#define SI570_REG_RFREQ4     12
> > +#define SI570_REG_CONTROL    135
> > +#define SI570_REG_FREEZE_DCO 137
> > +#define SI570_DIV_OFFSET_7PPM        6
> > +
> > +#define HS_DIV_SHIFT         5
> > +#define HS_DIV_MASK          0xe0
> > +#define HS_DIV_OFFSET                4
> > +#define N1_6_2_MASK          0x1f
> > +#define N1_1_0_MASK          0xc0
> > +#define RFREQ_37_32_MASK     0x3f
> > +
> > +#define SI570_MIN_FREQ               10000000L
> > +#define SI570_MAX_FREQ               1417500000L
> > +#define SI598_MAX_FREQ               525000000L
> > +
> > +#define FDCO_MIN             4850000000LL
> > +#define FDCO_MAX             5670000000LL
> > +
> > +#define SI570_CNTRL_RECALL   (1 << 0)
> > +#define SI570_CNTRL_FREEZE_M (1 << 5)
> > +#define SI570_CNTRL_NEWFREQ  (1 << 6)
> > +
> > +#define SI570_FREEZE_DCO     (1 << 4)
> > +
> > +/**
> > + * struct clk_si570:
> > + * @hw:      Clock hw struct
> > + * @regmap:  Device's regmap
> > + * @div_offset:      Rgister offset for dividers
> > + * @max_freq:        Maximum frequency for this device
> > + * @fxtal:   Factory xtal frequency
> > + * @n1:              Clock divider N1
> > + * @hs_div:  Clock divider HSDIV
> > + * @rfreq:   Clock multiplier RFREQ
> > + * @frequency:       Current output frequency
> > + * @i2c_client:      I2C client pointer
> > + */
> > +struct clk_si570 {
> > +     struct clk_hw hw;
> > +     struct regmap *regmap;
> > +     unsigned int div_offset;
> > +     u64 max_freq;
> > +     u64 fxtal;
> > +     unsigned int n1;
> > +     unsigned int hs_div;
> > +     u64 rfreq;
> > +     u64 frequency;
> > +     struct i2c_client *i2c_client;
> > +};
> > +#define to_clk_si570(_hw)    container_of(_hw, struct clk_si570, hw)
> > +
> > +enum clk_si570_variant {
> > +     si57x,
> > +     si59x
> > +};
> > +
> > +/**
> > + * si570_get_divs() - Read clock dividers from HW
> > + * @data:    Pointer to struct clk_si570
> > + * @rfreq:   Fractional multiplier (output)
> > + * @n1:              Divider N1 (output)
> > + * @hs_div:  Divider HSDIV (output)
> > + * Returns 0 on success, negative errno otherwise.
> > + *
> > + * Retrieve clock dividers and multipliers from the HW.
> > + */
> > +static int si570_get_divs(struct clk_si570 *data, u64 *rfreq,
> > +             unsigned int *n1, unsigned int *hs_div)
> > +{
> > +     int err;
> > +     u8 reg[6];
> > +     u64 tmp;
> > +
> > +     err = regmap_bulk_read(data->regmap, SI570_REG_HS_N1 + data->div_offset,
> > +                     reg, ARRAY_SIZE(reg));
> > +     if (err)
> > +             return err;
> > +
> > +     *hs_div = ((reg[0] & HS_DIV_MASK) >> HS_DIV_SHIFT) + HS_DIV_OFFSET;
> > +     *n1 = ((reg[0] & N1_6_2_MASK) << 2) + ((reg[1] & N1_1_0_MASK) >> 6) + 1;
> > +     /* Handle invalid cases */
> > +     if (*n1 > 1)
> > +             *n1 &= ~1;
> > +
> > +     tmp = reg[1] & RFREQ_37_32_MASK;
> > +     tmp = (tmp << 8) + reg[2];
> > +     tmp = (tmp << 8) + reg[3];
> > +     tmp = (tmp << 8) + reg[4];
> > +     tmp = (tmp << 8) + reg[5];
> > +     *rfreq = tmp;
> > +
> > +     return 0;
> > +}
> > +
> > +/**
> > + * si570_get_defaults() - Get default values
> > + * @data:    Driver data structure
> > + * @fout:    Factory frequency output
> > + * Returns 0 on success, negative errno otherwise.
> > + */
> > +static int si570_get_defaults(struct clk_si570 *data, u64 fout)
> > +{
> > +     int err;
> > +     u64 fdco;
> > +
> > +     regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_RECALL);
> > +
> > +     err = si570_get_divs(data, &data->rfreq, &data->n1, &data->hs_div);
> > +     if (err)
> > +             return err;
> > +
> > +     /*
> > +      * Accept optional precision loss to avoid arithmetic overflows.
> > +      * Acceptable per Silicon Labs Application Note AN334.
> > +      */
> > +     fdco = fout * data->n1 * data->hs_div;
> > +     if (fdco >= (1LL << 36))
> > +             data->fxtal = div64_u64(fdco << 24, data->rfreq >> 4);
> > +     else
> > +             data->fxtal = div64_u64(fdco << 28, data->rfreq);
> > +
> > +     data->frequency = fout;
> > +
> > +     return 0;
> > +}
> > +
> > +/**
> > + * si570_update_rfreq() - Update clock multiplier
> > + * @data:    Driver data structure
> > + * Passes on regmap_bulk_write() return value.
> > + */
> > +static int si570_update_rfreq(struct clk_si570 *data)
> > +{
> > +     u8 reg[5];
> > +
> > +     reg[0] = ((data->n1 - 1) << 6) |
> > +             ((data->rfreq >> 32) & RFREQ_37_32_MASK);
> > +     reg[1] = (data->rfreq >> 24) & 0xff;
> > +     reg[2] = (data->rfreq >> 16) & 0xff;
> > +     reg[3] = (data->rfreq >> 8) & 0xff;
> > +     reg[4] = data->rfreq & 0xff;
> > +
> > +     return regmap_bulk_write(data->regmap, SI570_REG_N1_RFREQ0 +
> > +                     data->div_offset, reg, ARRAY_SIZE(reg));
> > +}
> > +
> > +/**
> > + * si570_calc_divs() - Caluclate clock dividers
> > + * @frequency:       Target frequency
> > + * @data:    Driver data structure
> > + * @out_rfreq:       RFREG fractional multiplier (output)
> > + * @out_n1:  Clock divider N1 (output)
> > + * @out_hs_div:      Clock divider HSDIV (output)
> > + * Returns 0 on success, negative errno otherwise.
> > + *
> > + * Calculate the clock dividers (@out_hs_div, @out_n1) and clock multiplier
> > + * (@out_rfreq) for a given target @frequency.
> > + */
> > +static int si570_calc_divs(unsigned long frequency, struct clk_si570 *data,
> > +             u64 *out_rfreq, unsigned int *out_n1, unsigned int *out_hs_div)
> > +{
> > +     int i;
> > +     unsigned int n1, hs_div;
> > +     u64 fdco, best_fdco = ULLONG_MAX;
> > +     static const uint8_t si570_hs_div_values[] = { 11, 9, 7, 6, 5, 4 };
> > +
> > +     for (i = 0; i < ARRAY_SIZE(si570_hs_div_values); i++) {
> > +             hs_div = si570_hs_div_values[i];
> > +             /* Calculate lowest possible value for n1 */
> > +             n1 = div_u64(div_u64(FDCO_MIN, hs_div), frequency);
> > +             if (!n1 || (n1 & 1))
> > +                     n1++;
> > +             while (n1 <= 128) {
> > +                     fdco = (u64)frequency * (u64)hs_div * (u64)n1;
> > +                     if (fdco > FDCO_MAX)
> > +                             break;
> > +                     if (fdco >= FDCO_MIN && fdco < best_fdco) {
> > +                             *out_n1 = n1;
> > +                             *out_hs_div = hs_div;
> > +                             *out_rfreq = div64_u64(fdco << 28, data->fxtal);
> > +                             best_fdco = fdco;
> > +                     }
> > +                     n1 += (n1 == 1 ? 1 : 2);
> > +             }
> > +     }
> > +
> > +     if (best_fdco == ULLONG_MAX)
> > +             return -EINVAL;
> > +
> > +     return 0;
> > +}
> > +
> > +static unsigned long si570_recalc_rate(struct clk_hw *hw,
> > +             unsigned long parent_rate)
> > +{
> > +     int err;
> > +     u64 rfreq, rate;
> > +     unsigned int n1, hs_div;
> > +     struct clk_si570 *data = to_clk_si570(hw);
> > +
> > +     err = si570_get_divs(data, &rfreq, &n1, &hs_div);
> > +     if (err) {
> > +             dev_err(&data->i2c_client->dev, "unable to recalc rate\n");
> > +             return data->frequency;
> > +     }
> > +
> > +     rfreq = div_u64(rfreq, hs_div * n1);
> > +     rate = (data->fxtal * rfreq) >> 28;
> > +
> > +     return rate;
> > +}
> > +
> > +static long si570_round_rate(struct clk_hw *hw, unsigned long rate,
> > +             unsigned long *parent_rate)
> > +{
> > +     int err;
> > +     u64 rfreq;
> > +     unsigned int n1, hs_div;
> > +     struct clk_si570 *data = to_clk_si570(hw);
> > +
> > +     if (!rate)
> > +             return 0;
> > +
> > +     if (div64_u64(abs(rate - data->frequency) * 10000LL,
> > +                             data->frequency) < 35) {
> > +             rfreq = div64_u64((data->rfreq * rate) +
> > +                             div64_u64(data->frequency, 2), data->frequency);
> > +             n1 = data->n1;
> > +             hs_div = data->hs_div;
> > +
> > +     } else {
> > +             err = si570_calc_divs(rate, data, &rfreq, &n1, &hs_div);
> > +             if (err) {
> > +                     dev_err(&data->i2c_client->dev,
> > +                                     "unable to round rate\n");
> > +                     return 0;
> > +             }
> > +     }
> > +
> > +     return rate;
> > +}
> > +
> > +/**
> > + * si570_set_frequency() - Adjust output frequency
> > + * @data:    Driver data structure
> > + * @frequency:       Target frequency
> > + * Returns 0 on success.
> > + *
> > + * Update output frequency for big frequency changes (> 3,500 ppm).
> > + */
> > +static int si570_set_frequency(struct clk_si570 *data, unsigned long frequency)
> > +{
> > +     int err;
> > +
> > +     err = si570_calc_divs(frequency, data, &data->rfreq, &data->n1,
> > +                     &data->hs_div);
> > +     if (err)
> > +             return err;
> > +
> > +     /*
> > +      * The DCO reg should be accessed with a read-modify-write operation
> > +      * per AN334
> > +      */
> > +     regmap_write(data->regmap, SI570_REG_FREEZE_DCO, SI570_FREEZE_DCO);
> > +     regmap_write(data->regmap, SI570_REG_HS_N1 + data->div_offset,
> > +                     ((data->hs_div - HS_DIV_OFFSET) << HS_DIV_SHIFT) |
> > +                     (((data->n1 - 1) >> 2) & N1_6_2_MASK));
> > +     si570_update_rfreq(data);
> > +     regmap_write(data->regmap, SI570_REG_FREEZE_DCO, 0);
> > +     regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_NEWFREQ);
> > +
> > +     /* Applying a new frequency can take up to 10ms */
> > +     usleep_range(10000, 12000);
> > +
> > +     return 0;
> > +}
> > +
> > +/**
> > + * si570_set_frequency_small() - Adjust output frequency
> > + * @data:    Driver data structure
> > + * @frequency:       Target frequency
> > + * Returns 0 on success.
> > + *
> > + * Update output frequency for small frequency changes (< 3,500 ppm).
> > + */
> > +static int si570_set_frequency_small(struct clk_si570 *data,
> > +                                  unsigned long frequency)
> > +{
> > +     /*
> > +      * This is a re-implementation of DIV_ROUND_CLOSEST
> > +      * using the div64_u64 function lieu of letting the compiler
> > +      * insert EABI calls
> > +      */
> > +     data->rfreq = div64_u64((data->rfreq * frequency) +
> > +                     div_u64(data->frequency, 2), data->frequency);
> > +     regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_FREEZE_M);
> > +     si570_update_rfreq(data);
> > +     regmap_write(data->regmap, SI570_REG_CONTROL, 0);
> > +
> > +     /* Applying a new frequency (small change) can take up to 100us */
> > +     usleep_range(100, 200);
> > +
> > +     return 0;
> > +}
> > +
> > +static int si570_set_rate(struct clk_hw *hw, unsigned long rate,
> > +             unsigned long parent_rate)
> > +{
> > +     struct clk_si570 *data = to_clk_si570(hw);
> > +     struct i2c_client *client = data->i2c_client;
> > +     int err;
> > +
> > +     if (rate < SI570_MIN_FREQ || rate > data->max_freq) {
> > +             dev_err(&client->dev,
> > +                     "requested frequency %lu Hz is out of range\n", rate);
> > +             return -EINVAL;
> > +     }
> > +
> > +     if (div64_u64(abs(rate - data->frequency) * 10000LL,
> > +                             data->frequency) < 35)
> > +             err = si570_set_frequency_small(data, rate);
> > +     else
> > +             err = si570_set_frequency(data, rate);
> > +
> > +     if (err)
> > +             return err;
> > +
> > +     data->frequency = rate;
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct clk_ops si570_clk_ops = {
> > +     .recalc_rate = si570_recalc_rate,
> > +     .round_rate = si570_round_rate,
> > +     .set_rate = si570_set_rate,
> > +};
> > +
> > +static bool si570_regmap_is_volatile(struct device *dev, unsigned int reg)
> > +{
> > +     switch (reg) {
> > +     case SI570_REG_CONTROL:
> > +             return true;
> > +     default:
> > +             return false;
> > +     }
> > +}
> > +
> > +static bool si570_regmap_is_writeable(struct device *dev, unsigned int reg)
> > +{
> > +     switch (reg) {
> > +     case SI570_REG_HS_N1 ... (SI570_REG_RFREQ4 + SI570_DIV_OFFSET_7PPM):
> > +     case SI570_REG_CONTROL:
> > +     case SI570_REG_FREEZE_DCO:
> > +             return true;
> > +     default:
> > +             return false;
> > +     }
> > +}
> > +
> > +static struct regmap_config si570_regmap_config = {
> > +     .reg_bits = 8,
> > +     .val_bits = 8,
> > +     .cache_type = REGCACHE_RBTREE,
> > +     .max_register = 137,
> > +     .writeable_reg = si570_regmap_is_writeable,
> > +     .volatile_reg = si570_regmap_is_volatile,
> > +};
> > +
> > +static int si570_probe(struct i2c_client *client,
> > +             const struct i2c_device_id *id)
> > +{
> > +     struct clk_si570 *data;
> > +     struct clk_init_data init;
> > +     struct clk *clk;
> > +     u32 initial_fout, factory_fout, stability;
> > +     int err;
> > +     enum clk_si570_variant variant = id->driver_data;
> > +
> > +     data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
> > +     if (!data)
> > +             return -ENOMEM;
> > +
> > +     init.ops = &si570_clk_ops;
> > +     init.flags = CLK_IS_ROOT;
> > +     init.num_parents = 0;
> > +     data->hw.init = &init;
> > +     data->i2c_client = client;
> > +
> > +     if (variant == si57x) {
> > +             err = of_property_read_u32(client->dev.of_node,
> > +                             "temperature-stability", &stability);
> > +             if (err) {
> > +                     dev_err(&client->dev,
> > +                               "'temperature-stability' property missing\n");
> > +                     return err;
> > +             }
> > +             /* adjust register offsets for 7ppm devices */
> > +             if (stability == 7)
> > +                     data->div_offset = SI570_DIV_OFFSET_7PPM;
> > +
> > +             data->max_freq = SI570_MAX_FREQ;
> > +     } else {
> > +             data->max_freq = SI598_MAX_FREQ;
> > +     }
> > +
> > +     if (of_property_read_string(client->dev.of_node, "clock-output-names",
> > +                     &init.name))
> > +             init.name = client->dev.of_node->name;
> > +
> > +     err = of_property_read_u32(client->dev.of_node, "factory-fout",
> > +                     &factory_fout);
> > +     if (err) {
> > +             dev_err(&client->dev, "'factory-fout' property missing\n");
> > +             return err;
> > +     }
> > +
> > +     data->regmap = devm_regmap_init_i2c(client, &si570_regmap_config);
> > +     if (IS_ERR(data->regmap)) {
> > +             dev_err(&client->dev, "failed to allocate register map\n");
> > +             return PTR_ERR(data->regmap);
> > +     }
> > +
> > +     i2c_set_clientdata(client, data);
> > +     err = si570_get_defaults(data, factory_fout);
> > +     if (err)
> > +             return err;
> > +
> > +     clk = devm_clk_register(&client->dev, &data->hw);
> > +     if (IS_ERR(clk)) {
> > +             dev_err(&client->dev, "clock registration failed\n");
> > +             return PTR_ERR(clk);
> > +     }
> > +     err = of_clk_add_provider(client->dev.of_node, of_clk_src_simple_get,
> > +                     clk);
> > +     if (err) {
> > +             dev_err(&client->dev, "unable to add clk provider\n");
> > +             return err;
> > +     }
> > +
> > +     /* Read the requested initial output frequency from device tree */
> > +     if (!of_property_read_u32(client->dev.of_node, "clock-frequency",
> > +                             &initial_fout)) {
> > +             err = clk_set_rate(clk, initial_fout);
> > +             if (err) {
> > +                     of_clk_del_provider(client->dev.of_node);
> > +                     return err;
> > +             }
> > +     }
> > +
> > +     /* Display a message indicating that we've successfully registered */
> > +     dev_info(&client->dev, "registered, current frequency %llu Hz\n",
> > +                     data->frequency);
> > +
> > +     return 0;
> > +}
> > +
> > +static int si570_remove(struct i2c_client *client)
> > +{
> > +     of_clk_del_provider(client->dev.of_node);
> > +     return 0;
> > +}
> > +
> > +static const struct i2c_device_id si570_id[] = {
> > +     { "si570", si57x },
> > +     { "si571", si57x },
> > +     { "si598", si59x },
> > +     { "si599", si59x },
> > +     { }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, si570_id);
> > +
> > +static const struct of_device_id clk_si570_of_match[] = {
> > +     { .compatible = "silabs,si570" },
> > +     { .compatible = "silabs,si571" },
> > +     { .compatible = "silabs,si598" },
> > +     { .compatible = "silabs,si599" },
> > +     { },
> > +};
> > +MODULE_DEVICE_TABLE(of, clk_si570_of_match);
> > +
> > +static struct i2c_driver si570_driver = {
> > +     .driver = {
> > +             .name = "si570",
> > +             .of_match_table = of_match_ptr(clk_si570_of_match),
> > +     },
> > +     .probe          = si570_probe,
> > +     .remove         = si570_remove,
> > +     .id_table       = si570_id,
> > +};
> > +module_i2c_driver(si570_driver);
> > +
> > +MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
> > +MODULE_AUTHOR("Soeren Brinkmann <soren.brinkmann@xilinx.com");
> > +MODULE_DESCRIPTION("Si570 driver");
> > +MODULE_LICENSE("GPL");
> > -- 
> > 1.8.4
> > 
> >
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