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From: mturquette@linaro.org (Mike Turquette)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] clk: Add axi-clkgen driver
Date: Tue, 22 Jan 2013 09:55:52 -0800	[thread overview]
Message-ID: <20130122175552.24671.27893@quantum> (raw)
In-Reply-To: <1357755120-32735-1-git-send-email-lars@metafoo.de>

Quoting Lars-Peter Clausen (2013-01-09 10:12:00)
<snip>
> +static void axi_clkgen_write(struct axi_clkgen *axi_clkgen,
> +       unsigned int reg, unsigned int val)
> +{
> +       iowrite32(val, axi_clkgen->base + reg);

Silly question: any reason to use this over readl()?  This is more for
my understanding than a real criticism.

> +}
> +
> +static void axi_clkgen_read(struct axi_clkgen *axi_clkgen,
> +       unsigned int reg, unsigned int *val)
> +{
> +       *val = ioread32(axi_clkgen->base + reg);

Same as above, any reason to use this over writel?

<snip>
> +static unsigned long axi_clkgen_recalc_rate(struct clk_hw *clk_hw,
> +       unsigned long parent_rate)
> +{
> +       struct axi_clkgen *axi_clkgen = clk_hw_to_axi_clkgen(clk_hw);
> +       unsigned int d, m, dout;
> +       unsigned int reg;
> +
> +       axi_clkgen_read(axi_clkgen, AXI_CLKGEN_REG_CLK_OUT1, &reg);
> +       dout = (reg & 0x3f) + ((reg >> 6) & 0x3f);
> +       axi_clkgen_read(axi_clkgen, AXI_CLKGEN_REG_CLK_DIV, &reg);
> +       d = (reg & 0x3f) + ((reg >> 6) & 0x3f);
> +       axi_clkgen_read(axi_clkgen, AXI_CLKGEN_REG_CLK_FB1, &reg);
> +       m = (reg & 0x3f) + ((reg >> 6) & 0x3f);
> +
> +       if (d == 0 || dout == 0)
> +               return 0;
> +
> +       return parent_rate / d * m / dout;

Any chance of overflow here?  Maybe do_div should be used?

Regards,
Mike

  reply	other threads:[~2013-01-22 17:55 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-09 18:12 [PATCH] clk: Add axi-clkgen driver Lars-Peter Clausen
2013-01-09 18:12 ` Lars-Peter Clausen
2013-01-22 17:55 ` Mike Turquette [this message]
2013-01-23 10:00   ` Lars-Peter Clausen
2013-01-23 10:00     ` Lars-Peter Clausen
2013-01-23 10:27     ` Russell King - ARM Linux
2013-01-23 10:27       ` Russell King - ARM Linux
2013-01-23 10:49       ` Lars-Peter Clausen
2013-01-23 10:49         ` Lars-Peter Clausen
2013-01-23 10:57         ` Russell King - ARM Linux
2013-01-23 10:57           ` Russell King - ARM Linux
2013-01-22 18:08 ` Josh Cartwright
2013-01-22 18:08   ` Josh Cartwright
2013-01-23  9:57   ` Lars-Peter Clausen
2013-01-23  9:57     ` Lars-Peter Clausen

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