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Message-ID: <5357F3EC.8070203@gmail.com>
Date: Wed, 23 Apr 2014 19:10:04 +0200
From: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To: Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
Mike Turquette <mturquette@...aro.org>
CC: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] clk: berlin: add support for clocks
On 04/23/2014 07:03 PM, Sebastian Hesselbarth wrote:
> On 04/23/2014 04:01 PM, Alexandre Belloni wrote:
>> Add support for clocks having their own register set.
>>
>> Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
>> ---
>> drivers/clk/berlin/Makefile | 2 +-
>> drivers/clk/berlin/clk.c | 132 ++++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 133 insertions(+), 1 deletion(-)
>> create mode 100644 drivers/clk/berlin/clk.c
>>
>> diff --git a/drivers/clk/berlin/Makefile b/drivers/clk/berlin/Makefile
>> index 94859513de90..9bfa58eaf25a 100644
>> --- a/drivers/clk/berlin/Makefile
>> +++ b/drivers/clk/berlin/Makefile
>> @@ -1,4 +1,4 @@
>> -obj-y += pll.o
>> +obj-y += pll.o clk.o
>> obj-$(CONFIG_MACH_BERLIN_BG2) += pll-berlin2.o
>> obj-$(CONFIG_MACH_BERLIN_BG2CD) += pll-berlin2.o
>> obj-$(CONFIG_MACH_BERLIN_BG2Q) += pll-berlin2q.o
>> diff --git a/drivers/clk/berlin/clk.c b/drivers/clk/berlin/clk.c
>> new file mode 100644
>> index 000000000000..a0e688e5bead
>> --- /dev/null
>> +++ b/drivers/clk/berlin/clk.c
>> @@ -0,0 +1,132 @@
>> +/*
>> + * Copyright (c) 2014 Marvell Technology Group Ltd.
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope 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.
>> + *
>> + * You should have received a copy of the GNU General Public License along with
>> + * this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +#include <linux/bitops.h>
>> +#include <linux/clk-provider.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/slab.h>
>> +
>> +#include "common.h"
>> +
>> +#define CLKEN (1 << 0)
>
> Alexandre,
>
> please use BIT(n) instead of (1 << n).
>
>> +#define CLKPLLSEL_MASK 7
>> +#define CLKPLLSEL_SHIFT 1
>> +#define CLKPLLSWITCH (1 << 4)
>> +#define CLKSWITCH (1 << 5)
>> +#define CLKD3SWITCH (1 << 6)
>> +#define CLKSEL_MASK 7
>> +#define CLKSEL_SHIFT 7
>
> In general, I would change the above defines to CLK_SEL_MASK, i.e.
> add a _ after CLK. While at it (as it can be seen from the code
> below), also rename CLK_D3SWITCH to CLK_DIV3_SWITCH.
>
>> +
>> +struct berlin_clk {
>> + struct clk_hw hw;
>> + void __iomem *base;
>> +};
>> +
>> +#define to_berlin_clk(hw) container_of(hw, struct berlin_clk, hw)
>> +
>> +static u8 clk_div[] = {1, 2, 4, 6, 8, 12, 1, 1};
>> +
>> +static unsigned long berlin_clk_recalc_rate(struct clk_hw *hw,
>> + unsigned long parent_rate)
>> +{
>> + u32 val, divider;
>> + struct berlin_clk *clk = to_berlin_clk(hw);
>> +
>> + val = readl_relaxed(clk->base);
>> + if (val & CLKD3SWITCH)
>> + divider = 3;
>> + else {
>> + if (val & CLKSWITCH) {
>> + val >>= CLKSEL_SHIFT;
>> + val &= CLKSEL_MASK;
>> + divider = clk_div[val];
>> + } else
>> + divider = 1;
>> + }
>> +
>
> There are stylistic issues:
>
> if-else with one part being enclosed in {} requires both parts
> to be enclosed in those curly brackets, i.e.
>
> if (foo)
> bar;
> else {
> foobar;
> barfoo;
> }
>
> has to become
>
> if (foo) {
> bar;
> } else {
> foobar;
> barfoo;
> }
>
> How about writing the above
Grr, I wasn't done with my review but who the f*ck puts
"Send now" on ^D ?
So, how about writing the above
val = readl_relaxed(clk->base);
divider = 1;
if (val & CLKD3SWITCH) {
divider = 3;
} else if (val & CLKSWITCH) {
val >>= CLKSEL_SHIFT;
val &= CLKSEL_MASK;
divider = clk_div[val];
}
>> + return parent_rate / divider;
>> +}
>> +
>> +static u8 berlin_clk_get_parent(struct clk_hw *hw)
>> +{
>> + u32 val;
>> + struct berlin_clk *clk = to_berlin_clk(hw);
>> +
>> + val = readl_relaxed(clk->base);
>> + if (val & CLKPLLSWITCH) {
>> + val >>= CLKPLLSEL_SHIFT;
>> + val &= CLKPLLSEL_MASK;
>> + return val;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static const struct clk_ops berlin_clk_ops = {
>> + .recalc_rate = berlin_clk_recalc_rate,
>> + .get_parent = berlin_clk_get_parent,
>> +};
>> +
>> +static void __init berlin_clk_setup(struct device_node *np)
>> +{
>> + struct clk_init_data init;
>> + struct berlin_clk *bclk;
>> + struct clk *clk;
>> + const char **parent_names;
>> + int nparents, i, ret;
>> +
>> + bclk = kzalloc(sizeof(*bclk), GFP_KERNEL);
>> + if (WARN_ON(!bclk))
>> + return;
>> +
>> + bclk->base = of_iomap(np, 0);
>> + if (WARN_ON(!bclk->base))
>> + goto exit;
>> +
>> + nparents = of_clk_get_parent_count(np);
>> + if (WARN_ON(!nparents))
>> + goto exit;
>> +
>> + parent_names = kzalloc((sizeof(char *) * nparents), GFP_KERNEL);
No need to put () around the calculation above. Also, if you put
nparents in front it may be more readable.
Sebastian
>> + if (WARN_ON(!parent_names))
>> + goto exit;
>> +
>> + init.name = np->name;
>> + init.ops = &berlin_clk_ops;
>> + for (i = 0; i < nparents; i++) {
>> + parent_names[i] = of_clk_get_parent_name(np, i);
>> + if (!parent_names[i])
>> + break;
>> + }
>> + init.parent_names = parent_names;
>> + init.num_parents = i;
>> +
>> + bclk->hw.init = &init;
>> +
>> + clk = clk_register(NULL, &bclk->hw);
>> + kfree(parent_names);
>> + if (WARN_ON(IS_ERR(clk)))
>> + goto exit;
>> +
>> + ret = of_clk_add_provider(np, of_clk_src_simple_get, clk);
>> + WARN_ON(ret);
>> +
>> + return;
>> +exit:
>> + kfree(bclk);
>> +}
>> +
>> +CLK_OF_DECLARE(berlin_clk, "marvell,berlin-clk", berlin_clk_setup);
>>
>
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