[PATCH] arm: imx6: don't reset PFDs that are used by periph_clk

[Marc Ohlf]

Check if PLL2 PFD0 or PLL2 PFD2 is selected as clock source in
register CCM CBCMR->pre_periph_clk_sel or CCM CBCMR->pre_periph2_clk.
Don't reset the used PFDs to avoid system hang.

ported from https://github.com/Freescale/u-boot-fslc/
commit/9293d7fd502ce29302fadb8b4ccb9231ec0bcc66

Signed-off-by: Marc Ohlf <ohlf at mkt-sys.de>
---
 arch/arm/mach-imx/imx6.c | 58 +++++++++++++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 23 deletions(-)

diff --git a/arch/arm/mach-imx/imx6.c b/arch/arm/mach-imx/imx6.c
index 14a1cba..2b55a3c 100644
--- a/arch/arm/mach-imx/imx6.c
+++ b/arch/arm/mach-imx/imx6.c
@@ -16,6 +16,7 @@
 #include <io.h>
 #include <linux/sizes.h>
 #include <mfd/imx6q-iomuxc-gpr.h>
+#include <mach/clock-imx6.h>
 #include <mach/imx6.h>
 #include <mach/generic.h>
 #include <mach/revision.h>
@@ -44,6 +45,11 @@ static void imx6_init_lowlevel(void)
 	void __iomem *aips2 = (void *)MX6_AIPS2_ON_BASE_ADDR;
 	bool is_imx6q = __imx6_cpu_type() == IMX6_CPUTYPE_IMX6Q;
 	bool is_imx6d = __imx6_cpu_type() == IMX6_CPUTYPE_IMX6D;
+	uint32_t val_480;
+	uint32_t val_528;
+	uint32_t periph_sel_1;
+	uint32_t periph_sel_2;
+	uint32_t reg;
 
 	/*
 	 * Set all MPROTx to be non-bufferable, trusted for R/W,
@@ -68,32 +74,38 @@ static void imx6_init_lowlevel(void)
 	/* Due to hardware limitation, on MX6Q we need to gate/ungate all PFDs
 	 * to make sure PFD is working right, otherwise, PFDs may
 	 * not output clock after reset, MX6DL and MX6SL have added 396M pfd
-	 * workaround in ROM code, as bus clock need it
+	 * workaround in ROM code, as bus clock need it.
+	 * Don't reset PLL2 PFD0 / PLL2 PFD2 if is's used by periph_clk.
 	 */
 	if (is_imx6q || is_imx6d) {
-		writel(BM_ANADIG_PFD_480_PFD3_CLKGATE |
-		       BM_ANADIG_PFD_480_PFD2_CLKGATE |
-		       BM_ANADIG_PFD_480_PFD1_CLKGATE |
-		       BM_ANADIG_PFD_480_PFD0_CLKGATE,
-		       MX6_ANATOP_BASE_ADDR + HW_ANADIG_PFD_480_SET);
-		writel(BM_ANADIG_PFD_528_PFD3_CLKGATE |
-		       BM_ANADIG_PFD_528_PFD2_CLKGATE |
-		       BM_ANADIG_PFD_528_PFD1_CLKGATE |
-		       BM_ANADIG_PFD_528_PFD0_CLKGATE,
-		       MX6_ANATOP_BASE_ADDR + HW_ANADIG_PFD_528_SET);
-
-		writel(BM_ANADIG_PFD_480_PFD3_CLKGATE |
-		       BM_ANADIG_PFD_480_PFD2_CLKGATE |
-		       BM_ANADIG_PFD_480_PFD1_CLKGATE |
-		       BM_ANADIG_PFD_480_PFD0_CLKGATE,
-		       MX6_ANATOP_BASE_ADDR + HW_ANADIG_PFD_480_CLR);
-		writel(BM_ANADIG_PFD_528_PFD3_CLKGATE |
-		       BM_ANADIG_PFD_528_PFD2_CLKGATE |
-		       BM_ANADIG_PFD_528_PFD1_CLKGATE |
-		       BM_ANADIG_PFD_528_PFD0_CLKGATE,
-		       MX6_ANATOP_BASE_ADDR + HW_ANADIG_PFD_528_CLR);
-	}
+		val_480 = BM_ANADIG_PFD_480_PFD3_CLKGATE |
+			   BM_ANADIG_PFD_480_PFD2_CLKGATE |
+			   BM_ANADIG_PFD_480_PFD1_CLKGATE |
+			   BM_ANADIG_PFD_480_PFD0_CLKGATE;
+
+		val_528 = BM_ANADIG_PFD_528_PFD3_CLKGATE |
+			   BM_ANADIG_PFD_528_PFD1_CLKGATE;
+
+		reg = readl(MXC_CCM_CBCMR);
+		periph_sel_1 = (reg & MXC_CCM_CBCMR_PRE_PERIPH_CLK_SEL_MASK)
+			>> MXC_CCM_CBCMR_PRE_PERIPH_CLK_SEL_OFFSET;
+
+		periph_sel_2 = (reg & MXC_CCM_CBCMR_PRE_PERIPH2_CLK_SEL_MASK)
+			>> MXC_CCM_CBCMR_PRE_PERIPH2_CLK_SEL_OFFSET;
 
+		if ((periph_sel_1 != 0x2) && (periph_sel_2 != 0x2))
+			val_528 |= BM_ANADIG_PFD_528_PFD0_CLKGATE;
+
+		if ((periph_sel_1 != 0x1) && (periph_sel_2 != 0x1)
+		    && (periph_sel_1 != 0x3) && (periph_sel_2 != 0x3))
+			val_528 |= BM_ANADIG_PFD_528_PFD2_CLKGATE;
+
+		writel(val_480, MX6_ANATOP_BASE_ADDR + HW_ANADIG_PFD_480_SET);
+		writel(val_528, MX6_ANATOP_BASE_ADDR + HW_ANADIG_PFD_528_SET);
+
+		writel(val_480, MX6_ANATOP_BASE_ADDR + HW_ANADIG_PFD_480_CLR);
+		writel(val_528, MX6_ANATOP_BASE_ADDR + HW_ANADIG_PFD_528_CLR);
+	}
 }
 
 static void imx6_setup_ipu_qos(void)
-- 
2.7.4