[PATCH RFC 1/2] clk: sunxi: Add sun8i display support
Jean-Francois Moine
moinejf at free.fr
Fri Jan 8 09:50:27 PST 2016
On Wed, 6 Jan 2016 10:39:51 +0800
Chen-Yu Tsai <wens at csie.org> wrote:
> First of all, please include the clk subsystem maintainers and the
> linux-clk mailing list for all clk related patches.
OK.
> On Wed, Jan 6, 2016 at 2:28 AM, Jean-Francois Moine <moinejf at free.fr> wrote:
> > Add the clock types which are used by the sun8i family for video.
>
> These clocks first appeared in the A31.
Sorry, I have the documentation of only some sun8i SoCs.
> > Signed-off-by: Jean-Francois Moine <moinejf at free.fr>
> > ---
> > drivers/clk/sunxi/Makefile | 1 +
> > drivers/clk/sunxi/clk-sun8i-display.c | 247 ++++++++++++++++++++++++++++++++++
>
> Please split this into 2 patches, and 2 files: one for PLL3, named
> clk-sun6i-pll3.c, and one for the display mod clocks, named
> clk-sun6i-display.c
No problem.
[snip]
> > diff --git a/drivers/clk/sunxi/clk-sun8i-display.c b/drivers/clk/sunxi/clk-sun8i-display.c
> > new file mode 100644
> > index 0000000..eded572
> > --- /dev/null
> > +++ b/drivers/clk/sunxi/clk-sun8i-display.c
> > @@ -0,0 +1,247 @@
> > +/*
> > + * Copyright 2015 Jean-Francois Moine <moinejf at free.fr>
> > + *
> > + * 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/of_address.h>
> > +#include <linux/slab.h>
> > +#include <linux/spinlock.h>
> > +#include <linux/rational.h>
> > +#include <linux/delay.h>
> > +
> > +static DEFINE_SPINLOCK(sun8i_display_lock);
> > +
> > +/* PLL3 (video) and PLL10 (de) */
> > +struct clk_fact {
> > + struct clk_hw hw;
> > + void __iomem *reg;
> > +};
> > +#define to_clk_fact(_hw) container_of(_hw, struct clk_fact, hw)
>
> What does fact stand for?
pre-divide plus factor. Have you a better name?
> > +
> > +#define SUN8I_PLL3_MSHIFT 0
> > +#define SUN8I_PLL3_MMASK 0x0f
>
> You can use GENMASK for these. Note that GENMASK is inclusive on both ends.
>
> > +#define SUN8I_PLL3_NSHIFT 8
> > +#define SUN8I_PLL3_NMASK 0x7f
> > +#define SUN8I_PLL3_MODE_SEL 0x01000000
> > +#define SUN8I_PLL3_FRAC_CLK 0x02000000
>
> Please use the BIT() macros.
OK.
> > +
> > +static int sun8i_pll3_get_fact(unsigned long rate,
> > + unsigned long parent_rate,
> > + unsigned long *n, unsigned long *m)
> > +{
> > + if (rate == 297000000)
> > + return 1;
> > + if (rate == 270000000)
> > + return 0;
> > + rational_best_approximation(rate, parent_rate,
> > + SUN8I_PLL3_NMASK + 1, SUN8I_PLL3_MMASK + 1,
> > + n, m);
> > + return -1;
> > +}
> > +
> > +static unsigned long sun8i_pll3_recalc_rate(struct clk_hw *hw,
> > + unsigned long parent_rate)
> > +{
> > + struct clk_fact *fact = to_clk_fact(hw);
> > + u32 reg;
> > + u32 n, m;
> > +
> > + reg = readl(fact->reg);
> > + if (reg & SUN8I_PLL3_MODE_SEL) {
> > + n = (reg >> SUN8I_PLL3_NSHIFT) & SUN8I_PLL3_NMASK;
> > + m = (reg >> SUN8I_PLL3_MSHIFT) & SUN8I_PLL3_MMASK;
> > + return parent_rate / (m + 1) * (n + 1);
> > + }
> > + if (reg & SUN8I_PLL3_FRAC_CLK)
> > + return 297000000;
> > + return 270000000;
> > +}
> > +
> > +static long sun8i_pll3_round_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long *parent_rate)
> > +{
> > + int frac;
> > + unsigned long n, m;
> > +
> > + frac = sun8i_pll3_get_fact(rate, *parent_rate, &n, &m);
> > + if (frac == 1)
> > + return 297000000;
> > + if (frac == 0)
> > + return 270000000;
> > + return (*parent_rate * n) / m;
>
> The ordering is different from the one in recalc_rate. Considering
> integer rounding, would the results be different?
Maybe. But, you are right, 'm', as a pre-divider, should be before 'n'.
> > +}
> > +
> > +static int sun8i_pll3_set_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long parent_rate)
> > +{
> > + struct clk_fact *fact = to_clk_fact(hw);
> > + u32 reg;
> > + int frac;
> > + unsigned long n, m;
> > +
> > + reg = readl(fact->reg) &
> > + ~(SUN8I_PLL3_MODE_SEL |
> > + SUN8I_PLL3_FRAC_CLK |
> > + (SUN8I_PLL3_NMASK << SUN8I_PLL3_NSHIFT) |
> > + (SUN8I_PLL3_MMASK << SUN8I_PLL3_MSHIFT));
> > +
> > + frac = sun8i_pll3_get_fact(rate, parent_rate, &n, &m);
> > + if (frac == 1)
> > + reg |= SUN8I_PLL3_FRAC_CLK; /* 297MHz */
> > + else if (frac == 0)
> > + ; /* 270MHz */
> > + else
> > + reg |= SUN8I_PLL3_MODE_SEL |
> > + ((n - 1) << SUN8I_PLL3_NSHIFT) |
> > + ((m - 1) << SUN8I_PLL3_MSHIFT);
> > +
> > + writel(reg, fact->reg);
> > +
> > + /* delay 500us so pll stabilizes */
> > + __delay(500);
>
> Bit 28 indicates PLL lock, please use readl_poll_timeout() to check it.
I did not know about this useful macro.
> > +
> > + return 0;
> > +}
> > +
> > +static const struct clk_ops clk_sun8i_pll3_fact_ops = {
> > + .recalc_rate = sun8i_pll3_recalc_rate,
> > + .round_rate = sun8i_pll3_round_rate,
> > + .set_rate = sun8i_pll3_set_rate,
> > +};
> > +
> > +static void __init sun8i_pll3_setup(struct device_node *node)
> > +{
> > + const char *clk_name = node->name, *parent;
> > + struct clk_fact *fact;
> > + struct clk_gate *gate;
> > + void __iomem *reg;
> > + struct clk *clk;
> > +
> > + of_property_read_string(node, "clock-output-names", &clk_name);
> > + parent = of_clk_get_parent_name(node, 0);
> > +
> > + reg = of_io_request_and_map(node, 0, of_node_full_name(node));
> > + if (IS_ERR(reg)) {
> > + pr_err("%s: Could not map the clock registers\n", clk_name);
> > + return;
> > + }
> > +
> > + gate = kzalloc(sizeof(*gate), GFP_KERNEL);
> > + if (!gate)
> > + return;
>
> You should call release_mem_region() to release the iomem region you
> requested with of_io_request_and_map().
Right.
> > +
> > + gate->reg = reg;
> > + gate->bit_idx = 31;
> > + gate->lock = &sun8i_display_lock;
> > +
> > + fact = kzalloc(sizeof(*fact), GFP_KERNEL);
> > + if (!fact)
> > + goto free_gate;
> > +
> > + fact->reg = reg;
> > +
> > + clk = clk_register_composite(NULL, clk_name,
> > + &parent, 1,
> > + NULL, NULL,
> > + &fact->hw, &clk_sun8i_pll3_fact_ops,
> > + &gate->hw, &clk_gate_ops,
> > + 0);
> > + if (IS_ERR(clk)) {
> > + pr_err("%s: Couldn't register the clock\n", clk_name);
> > + goto free_fact;
> > + }
> > +
> > + of_clk_add_provider(node, of_clk_src_simple_get, clk);
>
> Would this fail?
Don't know. This is done this way in many other sunxi clocks.
> > +
> > + return;
> > +
> > +free_fact:
> > + kfree(fact);
> > +free_gate:
> > + kfree(gate);
> > +}
> > +
> > +CLK_OF_DECLARE(sun8i_pll3, "allwinner,sun8i-pll3-clk", sun8i_pll3_setup);
> > +
> > +/* DE, TCON0, TVE, HDMI, DEINTERLACE */
> > +static void __init sun8i_display_setup(struct device_node *node)
> > +{
> > + const char *clk_name = node->name;
> > + const char *parents[2];
>
> There are as many as six parents for display mod clocks on A31.
> A23/A33 mod clocks have holes in there parent array, as some
> PLLs are missing. We may need a different driver to deal with
> that.
I don't see why: the DT may contain dummy clocks in the parent list.
Otherwise, I agree the remaining remarks.
Thanks for the review.
--
Ken ar c'hentañ | ** Breizh ha Linux atav! **
Jef | http://moinejf.free.fr/
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