[PATCH 4/9] clk: imx: add pllv4 support

Dong Aisheng
2017-06-20T09:31:43Z

On Mon, Jun 19, 2017 at 06:59:17PM -0700, Stephen Boyd wrote:
> On 05/15, Dong Aisheng wrote:
> > obj-$(CONFIG_SOC_IMX1) += clk-imx1.o
> > diff --git a/drivers/clk/imx/clk-pllv4.c b/drivers/clk/imx/clk-pllv4.c
> > new file mode 100644
> > index 0000000..502da64
> > --- /dev/null
> > +++ b/drivers/clk/imx/clk-pllv4.c
> > @@ -0,0 +1,196 @@
> > +/*
> > + * Copyright (C) 2016 Freescale Semiconductor, Inc.
> > + * Copyright 2017 NXP
> > + *
> > + * Author: Dong Aisheng <aisheng.dong@nxp.com>
> > + *
> > + * 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.
> > + *
> > + * http://www.opensource.org/licenses/gpl-license.html
> > + * http://www.gnu.org/copyleft/gpl.html
> > + */
> > +
> > +#include <linux/clk-provider.h>
> > +#include <linux/clk.h>
>
> Is this include used?
>

Nice catch. Will remove.

> > +#include <linux/delay.h>
> > +#include <linux/err.h>
> > +#include <linux/slab.h>
> > +
> > +/* PLL Control Status Register (xPLLCSR) */
> > +#define PLL_CSR_OFFSET 0x0
> > +#define PLL_VLD BIT(24)
> > +#define PLL_EN BIT(0)
> > +
> > +/* PLL Configuration Register (xPLLCFG) */
> > +#define PLL_CFG_OFFSET 0x08
> > +#define BP_PLL_MULT 16
> > +#define BM_PLL_MULT (0x7f << 16)
> > +
> > +/* PLL Numerator Register (xPLLNUM) */
> > +#define PLL_NUM_OFFSET 0x10
> > +
> > +/* PLL Denominator Register (xPLLDENOM) */
> > +#define PLL_DENOM_OFFSET 0x14
> > +
> > +struct clk_pllv4 {
> > + struct clk_hw hw;
> > + void __iomem *base;
> > +};
> > +
> > +/* Valid PLL MULT Table */
> > +static const int pllv4_mult_table[] = {33, 27, 22, 20, 17, 16};
> > +
> > +#define to_clk_pllv4(__hw) container_of(__hw, struct clk_pllv4, hw)
> > +
> > +static int clk_pllv4_wait_lock(struct clk_pllv4 *pll)
> > +{
> > + unsigned long timeout = jiffies + msecs_to_jiffies(5);
> > +
> > + /* Wait for PLL to lock */
> > + do {
> > + if (readl_relaxed(pll->base + PLL_CSR_OFFSET) & PLL_VLD)
> > + break;
> > + if (time_after(jiffies, timeout))
> > + break;
> > + usleep_range(50, 500);
> > + } while (1);
> > +
> > + return readl_relaxed(pll->base + PLL_CSR_OFFSET) & PLL_VLD ?
> > + 0 : -ETIMEDOUT;
>
> Use readl_poll_timeout() instead?
>

Good idea.

> > +}
> > +
> > +static int clk_pllv4_is_enabled(struct clk_hw *hw)
> > +{
> > + struct clk_pllv4 *pll = to_clk_pllv4(hw);
> > +
> > + if (readl_relaxed(pll->base) & PLL_EN)
> > + return 1;
> > +
> > + return 0;
> > +}
> > +
> > +static unsigned long clk_pllv4_recalc_rate(struct clk_hw *hw,
> > + unsigned long parent_rate)
> > +{
> > + struct clk_pllv4 *pll = to_clk_pllv4(hw);
> > + u32 div;
> > +
> > + div = (readl_relaxed(pll->base + PLL_CFG_OFFSET)
> > + & BM_PLL_MULT) >> BP_PLL_MULT;
>
> Put that on multiple lines please:
>
> div = readl_relaxed(pll->base + PLL_CFG_OFFSET);
> div &= BM_PLL_MULT;
> div >>= BP_PLL_MULT; /* Why BP this time? */
>

Of course.

> > +
> > + return parent_rate * div;
> > +}
> > +
> > +static long clk_pllv4_round_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long *prate)
> > +{
> > + unsigned long parent_rate = *prate;
> > + unsigned long round_rate, i;
> > +
> > + for (i = 0; i < ARRAY_SIZE(pllv4_mult_table); i++) {
> > + round_rate = parent_rate * pllv4_mult_table[i];
> > + if (rate >= round_rate)
> > + return round_rate;
> > + }
> > +
> > + return round_rate;
> > +}
> > +
> > +static bool clk_pllv4_is_valid_mult(unsigned int mult)
> > +{
> > + int i;
> > +
> > + /* check if mult is in valid MULT table */
> > + for (i = 0; i < ARRAY_SIZE(pllv4_mult_table); i++) {
> > + if (pllv4_mult_table[i] == mult)
> > + return true;
> > + }
> > +
> > + return false;
> > +}
> > +
> > +static int clk_pllv4_set_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long parent_rate)
> > +{
> > + struct clk_pllv4 *pll = to_clk_pllv4(hw);
> > + u32 val, mult;
> > +
> > + if (clk_pllv4_is_enabled(hw)) {
> > + WARN(1, "clk_pllv4: can't change rate when pll is enabled");
> > + return -EINVAL;
>
> Sad, CLK_SET_RATE_GATE isn't working for you I suppose?
>

CLK_SET_RATE_GATE can't work in early stage before running clk_disable_unused.
At that point, the clock tree state is still not consistent with HW.
e.g. prepare/enable count is still zero but it's actually enabled due to
reset state or bootloader.

The code here is adding a double check in case user sets rate in early stage.

However, probably it could also be moved into clock core as it's not platform
dependant behavior?

Regards
Dong Aisheng

> > + }
> > +
> > + mult = rate / parent_rate;
> > +
> > + if (clk_pllv4_is_valid_mult(mult))
> > + return -EINVAL;
> > +
> > + val = readl_relaxed(pll->base + PLL_CFG_OFFSET);
> > + val &= ~BM_PLL_MULT;
> > + val |= mult << BP_PLL_MULT;
> > + writel_relaxed(val, pll->base + PLL_CFG_OFFSET);
> > +
> > + return 0;
> > +}
> > +
>
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