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Commit f3f739c9 authored by Lori Hikichi's avatar Lori Hikichi Committed by Stephen Boyd
Browse files

clk: iproc: Allow plls to do minor rate changes without reset 



The iproc plls are capable of doing small rate changes without the
need for a full reset and re-lock procedure.  This feature will
allow for small tweaks to the PLL rate to occur smoothly.

Signed-off-by: default avatarLori Hikichi <lori.hikichi@broadcom.com>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
parent 85151a6b

drivers/clk/bcm/clk-iproc-pll.c

+47 −0
Original line number Diff line number Diff line
@@ -285,6 +285,40 @@ static void __pll_bring_out_reset(struct iproc_pll *pll, unsigned int kp, 
	iproc_pll_write(pll, pll->control_base, reset->offset, val);

}



/*

 * Determines if the change to be applied to the PLL is minor (just an update

 * or the fractional divider). If so, then we can avoid going through a

 * disruptive reset and lock sequence.

 */

static bool pll_fractional_change_only(struct iproc_pll *pll,

				       struct iproc_pll_vco_param *vco)

{

	const struct iproc_pll_ctrl *ctrl = pll->ctrl;

	u32 val;

	u32 ndiv_int;

	unsigned int pdiv;



	/* PLL needs to be locked */

	val = readl(pll->status_base + ctrl->status.offset);

	if ((val & (1 << ctrl->status.shift)) == 0)

		return false;



	val = readl(pll->control_base + ctrl->ndiv_int.offset);

	ndiv_int = (val >> ctrl->ndiv_int.shift) &

		bit_mask(ctrl->ndiv_int.width);



	if (ndiv_int != vco->ndiv_int)

		return false;



	val = readl(pll->control_base + ctrl->pdiv.offset);

	pdiv = (val >> ctrl->pdiv.shift) & bit_mask(ctrl->pdiv.width);



	if (pdiv != vco->pdiv)

		return false;



	return true;

}



static int pll_set_rate(struct iproc_clk *clk, struct iproc_pll_vco_param *vco,

			unsigned long parent_rate)

{
@@ -333,6 +367,19 @@ static int pll_set_rate(struct iproc_clk *clk, struct iproc_pll_vco_param *vco, 
		return ret;

	}



	if (pll_fractional_change_only(clk->pll, vco)) {

		/* program fractional part of NDIV */

		if (ctrl->flags & IPROC_CLK_PLL_HAS_NDIV_FRAC) {

			val = readl(pll->control_base + ctrl->ndiv_frac.offset);

			val &= ~(bit_mask(ctrl->ndiv_frac.width) <<

				 ctrl->ndiv_frac.shift);

			val |= vco->ndiv_frac << ctrl->ndiv_frac.shift;

			iproc_pll_write(pll, pll->control_base,

					ctrl->ndiv_frac.offset, val);

			return 0;

		}

	}



	/* put PLL in reset */

	__pll_put_in_reset(pll);