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Message-ID: <5357F24B.8070405@gmail.com>
Date: Wed, 23 Apr 2014 19:03:07 +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 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
> + 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;
> + }
> + 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);
> + 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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