linux-kernel - [PATCH V2 3/4] clk: imx: sccg: use relaxed io api

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Date:   Thu, 14 Nov 2019 03:38:23 +0000
From:   Peng Fan <peng.fan@....com>
To:     "sboyd@...nel.org" <sboyd@...nel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        Abel Vesa <abel.vesa@....com>
CC:     "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>,
        Aisheng Dong <aisheng.dong@....com>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Leonard Crestez <leonard.crestez@....com>,
        Alice Guo <alice.guo@....com>,
        "will@...nel.org" <will@...nel.org>, Peng Fan <peng.fan@....com>
Subject: [PATCH V2 3/4] clk: imx: sccg: use relaxed io api

From: Peng Fan <peng.fan@....com>

writel/readl has a barrier, however that barrier is not needed,
because device memory mapping is nGnRE mapping and access is
in order and clk driver has spin lock or other lock to make
sure write finished. It is ok to use relaxed api here, no need
to use stronger readl/writel

Signed-off-by: Peng Fan <peng.fan@....com>
---
 drivers/clk/imx/clk-sccg-pll.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/clk/imx/clk-sccg-pll.c b/drivers/clk/imx/clk-sccg-pll.c
index 2cf874813458..e03f8acb1e82 100644
--- a/drivers/clk/imx/clk-sccg-pll.c
+++ b/drivers/clk/imx/clk-sccg-pll.c
@@ -106,8 +106,9 @@ static int clk_sccg_pll_wait_lock(struct clk_sccg_pll *pll)
 
 	/* don't wait for lock if all plls are bypassed */
 	if (!(val & SSCG_PLL_BYPASS2_MASK))
-		return readl_poll_timeout(pll->base, val, val & PLL_LOCK_MASK,
-						0, PLL_SCCG_LOCK_TIMEOUT);
+		return readl_relaxed_poll_timeout(pll->base, val,
+						  val & PLL_LOCK_MASK,
+						  0, PLL_SCCG_LOCK_TIMEOUT);
 
 	return 0;
 }
@@ -349,7 +350,7 @@ static unsigned long clk_sccg_pll_recalc_rate(struct clk_hw *hw,
 
 	temp64 = parent_rate;
 
-	val = readl(pll->base + PLL_CFG0);
+	val = readl_relaxed(pll->base + PLL_CFG0);
 	if (val & SSCG_PLL_BYPASS2_MASK) {
 		temp64 = parent_rate;
 	} else if (val & SSCG_PLL_BYPASS1_MASK) {
@@ -372,10 +373,10 @@ static int clk_sccg_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 	u32 val;
 
 	/* set bypass here too since the parent might be the same */
-	val = readl(pll->base + PLL_CFG0);
+	val = readl_relaxed(pll->base + PLL_CFG0);
 	val &= ~SSCG_PLL_BYPASS_MASK;
 	val |= FIELD_PREP(SSCG_PLL_BYPASS_MASK, setup->bypass);
-	writel(val, pll->base + PLL_CFG0);
+	writel_relaxed(val, pll->base + PLL_CFG0);
 
 	val = readl_relaxed(pll->base + PLL_CFG2);
 	val &= ~(PLL_DIVF1_MASK | PLL_DIVF2_MASK);
@@ -396,7 +397,7 @@ static u8 clk_sccg_pll_get_parent(struct clk_hw *hw)
 	u32 val;
 	u8 ret = pll->parent;
 
-	val = readl(pll->base + PLL_CFG0);
+	val = readl_relaxed(pll->base + PLL_CFG0);
 	if (val & SSCG_PLL_BYPASS2_MASK)
 		ret = pll->bypass2;
 	else if (val & SSCG_PLL_BYPASS1_MASK)
@@ -409,10 +410,10 @@ static int clk_sccg_pll_set_parent(struct clk_hw *hw, u8 index)
 	struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
 	u32 val;
 
-	val = readl(pll->base + PLL_CFG0);
+	val = readl_relaxed(pll->base + PLL_CFG0);
 	val &= ~SSCG_PLL_BYPASS_MASK;
 	val |= FIELD_PREP(SSCG_PLL_BYPASS_MASK, pll->setup.bypass);
-	writel(val, pll->base + PLL_CFG0);
+	writel_relaxed(val, pll->base + PLL_CFG0);
 
 	return clk_sccg_pll_wait_lock(pll);
 }
-- 
2.16.4