diff mbox series

[V2] clk: imx: pllv4: add fractional-N pll support

Message ID 1556585557-28795-1-git-send-email-Anson.Huang@nxp.com (mailing list archive)
State Mainlined, archived
Commit a048fe996b5109d3c94c243bb0733419fbd0ed8f
Headers show
Series [V2] clk: imx: pllv4: add fractional-N pll support | expand

Commit Message

Anson Huang April 30, 2019, 12:57 a.m. UTC
The pllv4 supports fractional-N function, the formula is:

PLL output freq = input * (mult + num/denom),

This patch adds fractional-N function support, including
clock round rate, calculate rate and set rate, with this
patch, the clock rate of APLL in clock tree is more accurate
than before:

Without fraction:
apll_pre_sel                      1        1        1    24000000          0     0  50000
   apll_pre_div                   1        1        2    24000000          0     0  50000
      apll                        1        1        2   528000000          0     0  50000
         apll_pfd3                0        0        0   792000000          0     0  50000
         apll_pfd2                0        0        0   339428571          0     0  50000
         apll_pfd1                0        0        0   352000000          0     0  50000
            usdhc0                0        0        0   352000000          0     0  50000
         apll_pfd0                1        1        1   352000000          0     0  50000

With fraction:
apll_pre_sel                      1        1        1    24000000          0     0  50000
   apll_pre_div                   1        1        2    24000000          0     0  50000
      apll                        1        1        2   529200000          0     0  50000
         apll_pfd3                0        0        0   793800000          0     0  50000
         apll_pfd2                0        0        0   340200000          0     0  50000
         apll_pfd1                0        0        0   352800000          0     0  50000
            usdhc0                0        0        0   352800000          0     0  50000
         apll_pfd0                1        1        1   352800000          0     0  50000

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
---
 drivers/clk/imx/clk-pllv4.c | 72 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 63 insertions(+), 9 deletions(-)

Comments

Stephen Boyd May 1, 2019, 9 p.m. UTC | #1
The Content-transfer-encoding header is still base64. I guess it can't
be fixed.

Quoting Anson Huang (2019-04-29 17:57:22)
> The pllv4 supports fractional-N function, the formula is:
> 
> PLL output freq = input * (mult + num/denom),
> 
> This patch adds fractional-N function support, including
> clock round rate, calculate rate and set rate, with this
> patch, the clock rate of APLL in clock tree is more accurate
> than before:
>
Aisheng Dong May 3, 2019, 2:38 a.m. UTC | #2
> From: Stephen Boyd [mailto:sboyd@kernel.org]
> Sent: Thursday, May 2, 2019 5:01 AM
> 
> The Content-transfer-encoding header is still base64. I guess it can't be fixed.
> 

How can we know it's base64?
As I saw from the 'Headers' in patchwork, it's:
"Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit"
https://patchwork.kernel.org/patch/10922657/

We'd like to fix it this.

Regards
Dong Aisheng

> Quoting Anson Huang (2019-04-29 17:57:22)
> > The pllv4 supports fractional-N function, the formula is:
> >
> > PLL output freq = input * (mult + num/denom),
> >
> > This patch adds fractional-N function support, including clock round
> > rate, calculate rate and set rate, with this patch, the clock rate of
> > APLL in clock tree is more accurate than before:
> >
Anson Huang May 3, 2019, 1 p.m. UTC | #3
Hi, Stephen

> -----Original Message-----
> From: Stephen Boyd [mailto:sboyd@kernel.org]
> Sent: Thursday, May 2, 2019 5:01 AM
> To: festevam@gmail.com; kernel@pengutronix.de; linux-arm-
> kernel@lists.infradead.org; linux-clk@vger.kernel.org; linux-
> kernel@vger.kernel.org; mturquette@baylibre.com;
> s.hauer@pengutronix.de; shawnguo@kernel.org; Aisheng Dong
> <aisheng.dong@nxp.com>; Anson Huang <anson.huang@nxp.com>
> Cc: dl-linux-imx <linux-imx@nxp.com>
> Subject: Re: [PATCH V2] clk: imx: pllv4: add fractional-N pll support
> 
> The Content-transfer-encoding header is still base64. I guess it can't be fixed.

Below is my git sendmail configuration, the encoding is set to UTF-8, I don't know
why it is still base64, let me know if you know how to fix it, thanks. And, will you still
review this patch? 

Anson.

  6 [sendemail]
  7         smtpserver = outlook.office365.com
  8         smtpencryption = tls
  9         smtpuser = Anson.Huang@nxp.com
 10         smtpserverport = 587
 11         confirm = never
 12         assume8bitEncoding = UTF-8


> 
> Quoting Anson Huang (2019-04-29 17:57:22)
> > The pllv4 supports fractional-N function, the formula is:
> >
> > PLL output freq = input * (mult + num/denom),
> >
> > This patch adds fractional-N function support, including clock round
> > rate, calculate rate and set rate, with this patch, the clock rate of
> > APLL in clock tree is more accurate than before:
> >
Stephen Boyd May 3, 2019, 3:57 p.m. UTC | #4
Quoting Aisheng Dong (2019-05-02 19:38:34)
> > From: Stephen Boyd [mailto:sboyd@kernel.org]
> > Sent: Thursday, May 2, 2019 5:01 AM
> > 
> > The Content-transfer-encoding header is still base64. I guess it can't be fixed.
> > 
> 
> How can we know it's base64?
> As I saw from the 'Headers' in patchwork, it's:
> "Content-Type: text/plain; charset="us-ascii"
> Content-Transfer-Encoding: 7bit"
> https://patchwork.kernel.org/patch/10922657/
> 
> We'd like to fix it this.
> 

I see:

Content-Type                                      text/plain; charset="utf-8"                                                                                                        
Content-Transfer-Encoding                         base64               

Maybe that's because I'm getting the mail directly instead of from the
mailing list?
Stephen Boyd May 3, 2019, 4 p.m. UTC | #5
Quoting Aisheng Dong (2019-05-02 19:38:34)
> > From: Stephen Boyd [mailto:sboyd@kernel.org]
> > Sent: Thursday, May 2, 2019 5:01 AM
> > 
> > The Content-transfer-encoding header is still base64. I guess it can't be fixed.
> > 
> 
> How can we know it's base64?
> As I saw from the 'Headers' in patchwork, it's:
> "Content-Type: text/plain; charset="us-ascii"
> Content-Transfer-Encoding: 7bit"
> https://patchwork.kernel.org/patch/10922657/
> 
> We'd like to fix it this.
> 

Also, if you look at the one for linux-clk mailing list you'll see
base64 CTE: https://patchwork.kernel.org/patch/10921115/
Aisheng Dong May 5, 2019, 6:18 a.m. UTC | #6
> From: Stephen Boyd [mailto:sboyd@kernel.org]
> Sent: Saturday, May 4, 2019 12:01 AM
> Subject: RE: [PATCH V2] clk: imx: pllv4: add fractional-N pll support
> 
> Quoting Aisheng Dong (2019-05-02 19:38:34)
> > > From: Stephen Boyd [mailto:sboyd@kernel.org]
> > > Sent: Thursday, May 2, 2019 5:01 AM
> > >
> > > The Content-transfer-encoding header is still base64. I guess it can't be
> fixed.
> > >
> > How can we know it's base64?
> > As I saw from the 'Headers' in patchwork, it's:
> > "Content-Type: text/plain; charset="us-ascii"
> > Content-Transfer-Encoding: 7bit"
> >
> > https://patchwork.kernel.org/patch/10922657/
> >
> > We'd like to fix it this.
> >
> 
> Also, if you look at the one for linux-clk mailing list you'll see
> base64 CTE:
> https://patchwork.kernel.org/patch/10921115/

We suspect it's our server configuration issue.
I've already submitted a ticket for our IT department to check.

BTW, for why we did not see base64 encoding from arm Linux maillist,
Not sure if it's automatically converted to 8bit encoding by arm-linux
maillist patchwork.

Regards
Dong Aisheng
diff mbox series

Patch

diff --git a/drivers/clk/imx/clk-pllv4.c b/drivers/clk/imx/clk-pllv4.c
index d38bc9f..d7e62c3 100644
--- a/drivers/clk/imx/clk-pllv4.c
+++ b/drivers/clk/imx/clk-pllv4.c
@@ -30,6 +30,9 @@ 
 /* PLL Denominator Register (xPLLDENOM) */
 #define PLL_DENOM_OFFSET	0x14
 
+#define MAX_MFD			0x3fffffff
+#define DEFAULT_MFD		1000000
+
 struct clk_pllv4 {
 	struct clk_hw	hw;
 	void __iomem	*base;
@@ -64,13 +67,20 @@  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;
+	u32 mult, mfn, mfd;
+	u64 temp64;
+
+	mult = readl_relaxed(pll->base + PLL_CFG_OFFSET);
+	mult &= BM_PLL_MULT;
+	mult >>= BP_PLL_MULT;
 
-	div = readl_relaxed(pll->base + PLL_CFG_OFFSET);
-	div &= BM_PLL_MULT;
-	div >>= BP_PLL_MULT;
+	mfn = readl_relaxed(pll->base + PLL_NUM_OFFSET);
+	mfd = readl_relaxed(pll->base + PLL_DENOM_OFFSET);
+	temp64 = parent_rate;
+	temp64 *= mfn;
+	do_div(temp64, mfd);
 
-	return parent_rate * div;
+	return (parent_rate * mult) + (u32)temp64;
 }
 
 static long clk_pllv4_round_rate(struct clk_hw *hw, unsigned long rate,
@@ -78,14 +88,46 @@  static long clk_pllv4_round_rate(struct clk_hw *hw, unsigned long rate,
 {
 	unsigned long parent_rate = *prate;
 	unsigned long round_rate, i;
+	u32 mfn, mfd = DEFAULT_MFD;
+	bool found = false;
+	u64 temp64;
 
 	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;
+		if (rate >= round_rate) {
+			found = true;
+			break;
+		}
+	}
+
+	if (!found) {
+		pr_warn("%s: unable to round rate %lu, parent rate %lu\n",
+			clk_hw_get_name(hw), rate, parent_rate);
+		return 0;
 	}
 
-	return round_rate;
+	if (parent_rate <= MAX_MFD)
+		mfd = parent_rate;
+
+	temp64 = (u64)(rate - round_rate);
+	temp64 *= mfd;
+	do_div(temp64, parent_rate);
+	mfn = temp64;
+
+	/*
+	 * NOTE: The value of numerator must always be configured to be
+	 * less than the value of the denominator. If we can't get a proper
+	 * pair of mfn/mfd, we simply return the round_rate without using
+	 * the frac part.
+	 */
+	if (mfn >= mfd)
+		return round_rate;
+
+	temp64 = (u64)parent_rate;
+	temp64 *= mfn;
+	do_div(temp64, mfd);
+
+	return round_rate + (u32)temp64;
 }
 
 static bool clk_pllv4_is_valid_mult(unsigned int mult)
@@ -105,18 +147,30 @@  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;
+	u32 val, mult, mfn, mfd = DEFAULT_MFD;
+	u64 temp64;
 
 	mult = rate / parent_rate;
 
 	if (!clk_pllv4_is_valid_mult(mult))
 		return -EINVAL;
 
+	if (parent_rate <= MAX_MFD)
+		mfd = parent_rate;
+
+	temp64 = (u64)(rate - mult * parent_rate);
+	temp64 *= mfd;
+	do_div(temp64, parent_rate);
+	mfn = temp64;
+
 	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);
 
+	writel_relaxed(mfn, pll->base + PLL_NUM_OFFSET);
+	writel_relaxed(mfd, pll->base + PLL_DENOM_OFFSET);
+
 	return 0;
 }