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Message-ID: <20140701172616.32686.44374@quantum>
Date: Tue, 01 Jul 2014 10:26:16 -0700
From: Mike Turquette <mturquette@...aro.org>
To: Yadwinder Singh Brar <yadi.brar01@...il.com>,
"Javier Martinez Canillas" <javier.martinez@...labora.co.uk>
Cc: "Lee Jones" <lee.jones@...aro.org>,
"Samuel Ortiz" <sameo@...ux.intel.com>,
"Mark Brown" <broonie@...nel.org>,
"Liam Girdwood" <lgirdwood@...il.com>,
"Alessandro Zummo" <a.zummo@...ertech.it>,
"Kukjin Kim" <kgene.kim@...sung.com>,
"Doug Anderson" <dianders@...omium.org>,
"Olof Johansson" <olof@...om.net>,
"Sjoerd Simons" <sjoerd.simons@...labora.co.uk>,
"Daniel Stone" <daniels@...labora.com>,
"Tomeu Vizoso" <tomeu.vizoso@...labora.com>,
"Krzysztof Kozlowski" <k.kozlowski@...sung.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"devicetree" <devicetree@...r.kernel.org>,
"linux-samsung-soc" <linux-samsung-soc@...r.kernel.org>,
"linux-kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 05/14] clk: Add generic driver for Maxim PMIC clocks
Quoting Yadwinder Singh Brar (2014-06-29 21:01:36)
> Hi Javier,
>
> On Thu, Jun 26, 2014 at 11:45 PM, Javier Martinez Canillas
> <javier.martinez@...labora.co.uk> wrote:
> > Maxim Integrated Power Management ICs are very similar with
> > regard to their clock outputs. Most of the clock drivers for
> > these chips are duplicating code and are simpler enough that
> > can be converted to use a generic driver to consolidate code
> > and avoid duplication.
> >
> > Signed-off-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
> > Reviewed-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> > ---
> >
> > Changes since v4:
> > - Return recalc 0 if clock isn't enabled in Suggested by Yadwinder Singh Brar.
> >
>
> It seems you didn't implement or posted same patch again :) .
>
> > Changes since v3:
> > - Add current copyright information. Suggested by Krzysztof Kozlowski
> > - Do a single allocation for struct max_gen_clk. Suggested by Krzysztof Kozlowski
> > - Add EXPORT_SYMBOL() for exported symbols. Suggested by Krzysztof Kozlowski
> >
> > drivers/clk/Kconfig | 3 +
> > drivers/clk/Makefile | 1 +
> > drivers/clk/clk-max-gen.c | 195 ++++++++++++++++++++++++++++++++++++++++++++++
> > drivers/clk/clk-max-gen.h | 32 ++++++++
> > 4 files changed, 231 insertions(+)
> > create mode 100644 drivers/clk/clk-max-gen.c
> > create mode 100644 drivers/clk/clk-max-gen.h
> >
>
> [ .. ]
>
> > +
> > +static unsigned long max_gen_recalc_rate(struct clk_hw *hw,
> > + unsigned long parent_rate)
> > +{
> > + return 32768;
> > +}
>
> Its still same here.
Changing this would be a new behavior. I do not know of any other clock
drivers that conditionally returns a rate of 0 based on whether or not
the clock is gated.
It is also buggy since calls to clk_enable and clk_disable do not invoke
.recalc_rate, so the rate of your clock would not be updated from the
framework's perspective until some later point where you call
clk_set_rate or something.
If your driver needs to know whether or not the clock is enabled then we
could introduce a new bool clk_is_enabled(struct clk *clk); to clk.h,
but I'd rather not do that. Instead if a driver needs a clock then it
calls clk_enable on it without any knowledge about the internal state of
the clock enable_count.
Regards,
Mike
>
> > +
> > +struct clk_ops max_gen_clk_ops = {
> > + .prepare = max_gen_clk_prepare,
> > + .unprepare = max_gen_clk_unprepare,
> > + .is_prepared = max_gen_clk_is_prepared,
> > + .recalc_rate = max_gen_recalc_rate,
> > +};
> > +EXPORT_SYMBOL_GPL(max_gen_clk_ops);
> > +
> > +static struct clk *max_gen_clk_register(struct device *dev,
> > + struct max_gen_clk *max_gen)
> > +{
> > + struct clk *clk;
> > + struct clk_hw *hw = &max_gen->hw;
> > +
> > + clk = clk_register(dev, hw);
> > + if (IS_ERR(clk))
> > + return clk;
> > +
> > + max_gen->lookup = kzalloc(sizeof(struct clk_lookup), GFP_KERNEL);
>
> As I suggested in other patch[1] also, its better to use
> clkdev_alloc() instead of kzalloc() here.
>
> > + if (!max_gen->lookup)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + max_gen->lookup->con_id = hw->init->name;
>
> Also IMO, init->name should be over-written if name is provided in DT,
> otherwise generic "clock-output-names" property will go futile,
> perhaps it should be done before clk_register.
>
> Regards,
> Yadwinder
>
> [1] : https://lkml.org/lkml/2014/6/27/197
>
> > + max_gen->lookup->clk = clk;
> > +
> > + clkdev_add(max_gen->lookup);
> > +
> > + return clk;
> > +}
> > +
> > +int max_gen_clk_probe(struct platform_device *pdev, struct regmap *regmap,
> > + u32 reg, struct clk_init_data *clks_init, int num_init)
> > +{
> > + int i, ret;
> > + struct max_gen_clk *max_gen_clks;
> > + struct clk **clocks;
> > + struct device *dev = &pdev->dev;
> > +
> > + clocks = devm_kzalloc(dev, sizeof(struct clk *) * num_init, GFP_KERNEL);
> > + if (!clocks)
> > + return -ENOMEM;
> > +
> > + max_gen_clks = devm_kzalloc(dev, sizeof(struct max_gen_clk)
> > + * num_init, GFP_KERNEL);
> > + if (!max_gen_clks)
> > + return -ENOMEM;
> > +
> > + for (i = 0; i < num_init; i++) {
> > + max_gen_clks[i].regmap = regmap;
> > + max_gen_clks[i].mask = 1 << i;
> > + max_gen_clks[i].reg = reg;
> > + max_gen_clks[i].hw.init = &clks_init[i];
> > +
> > + clocks[i] = max_gen_clk_register(dev, &max_gen_clks[i]);
> > + if (IS_ERR(clocks[i])) {
> > + ret = PTR_ERR(clocks[i]);
> > + dev_err(dev, "failed to register %s\n",
> > + max_gen_clks[i].hw.init->name);
> > + goto err_clocks;
> > + }
> > + }
> > +
> > + platform_set_drvdata(pdev, clocks);
> > +
> > + if (dev->of_node) {
> > + struct clk_onecell_data *of_data;
> > +
> > + of_data = devm_kzalloc(dev, sizeof(*of_data), GFP_KERNEL);
> > + if (!of_data) {
> > + ret = -ENOMEM;
> > + goto err_clocks;
> > + }
> > +
> > + of_data->clks = clocks;
> > + of_data->clk_num = num_init;
> > + ret = of_clk_add_provider(dev->of_node, of_clk_src_onecell_get,
> > + of_data);
> > +
> > + if (ret) {
> > + dev_err(dev, "failed to register OF clock provider\n");
> > + goto err_clocks;
> > + }
> > + }
> > +
> > + return 0;
> > +
> > +err_clocks:
> > + for (--i; i >= 0; --i) {
> > + clkdev_drop(max_gen_clks[i].lookup);
> > + clk_unregister(max_gen_clks[i].hw.clk);
> > + }
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(max_gen_clk_probe);
> > +
> > +int max_gen_clk_remove(struct platform_device *pdev, int num_init)
> > +{
> > + struct clk **clocks = platform_get_drvdata(pdev);
> > + struct device *dev = pdev->dev.parent;
> > + int i;
> > +
> > + if (dev->of_node)
> > + of_clk_del_provider(dev->of_node);
> > +
> > + for (i = 0; i < num_init; i++) {
> > + struct clk_hw *hw = __clk_get_hw(clocks[i]);
> > + struct max_gen_clk *max_gen = to_max_gen_clk(hw);
> > +
> > + clkdev_drop(max_gen->lookup);
> > + clk_unregister(clocks[i]);
> > + }
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(max_gen_clk_remove);
> > diff --git a/drivers/clk/clk-max-gen.h b/drivers/clk/clk-max-gen.h
> > new file mode 100644
> > index 0000000..997e86f
> > --- /dev/null
> > +++ b/drivers/clk/clk-max-gen.h
> > @@ -0,0 +1,32 @@
> > +/*
> > + * clk-max-gen.h - Generic clock driver for Maxim PMICs clocks
> > + *
> > + * Copyright (C) 2014 Google, Inc
> > + *
> > + * 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.
> > + *
> > + */
> > +
> > +#ifndef __CLK_MAX_GEN_H__
> > +#define __CLK_MAX_GEN_H__
> > +
> > +#include <linux/types.h>
> > +#include <linux/device.h>
> > +#include <linux/clkdev.h>
> > +#include <linux/regmap.h>
> > +#include <linux/platform_device.h>
> > +
> > +int max_gen_clk_probe(struct platform_device *pdev, struct regmap *regmap,
> > + u32 reg, struct clk_init_data *clks_init, int num_init);
> > +int max_gen_clk_remove(struct platform_device *pdev, int num_init);
> > +extern struct clk_ops max_gen_clk_ops;
> > +
> > +#endif /* __CLK_MAX_GEN_H__ */
> > --
> > 2.0.0.rc2
> >
--
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