soc: xilinx: vcu: implement PLL disable

The disabling of the PLL is not fully implemented, because according to
the ZynqMP register reference the RESET, POR_IN and PWR_POR bits have to
be set to bring the PLL into reset.

Set the bits to disable the PLL.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/20210121071659.1226489-7-m.tretter@pengutronix.de
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: tretter

drivers/soc/xilinx/xlnx_vcu.c

@@ -329,6 +329,10 @@ static int xvcu_pll_enable(struct xvcu_device *xvcu)
 		return ret;
 	}
 
+	xvcu_write_field_reg(base, VCU_PLL_CTRL,
+			     1, VCU_PLL_CTRL_BYPASS_MASK,
+			     VCU_PLL_CTRL_BYPASS_SHIFT);
+
 	vcu_pll_ctrl = xvcu_read(base, VCU_PLL_CTRL);
 	vcu_pll_ctrl &= ~(VCU_PLL_CTRL_POR_IN_MASK <<
 			  VCU_PLL_CTRL_POR_IN_SHIFT);
@@ -340,15 +344,9 @@ static int xvcu_pll_enable(struct xvcu_device *xvcu)
 			 VCU_PLL_CTRL_PWR_POR_SHIFT;
 	xvcu_write(base, VCU_PLL_CTRL, vcu_pll_ctrl);
 
-	xvcu_write_field_reg(base, VCU_PLL_CTRL,
-			     1, VCU_PLL_CTRL_BYPASS_MASK,
-			     VCU_PLL_CTRL_BYPASS_SHIFT);
-	xvcu_write_field_reg(base, VCU_PLL_CTRL,
-			     1, VCU_PLL_CTRL_RESET_MASK,
-			     VCU_PLL_CTRL_RESET_SHIFT);
-	xvcu_write_field_reg(base, VCU_PLL_CTRL,
-			     0, VCU_PLL_CTRL_RESET_MASK,
-			     VCU_PLL_CTRL_RESET_SHIFT);
+	vcu_pll_ctrl &= ~(VCU_PLL_CTRL_RESET_MASK << VCU_PLL_CTRL_RESET_SHIFT);
+	vcu_pll_ctrl |= (0 & VCU_PLL_CTRL_RESET_MASK) << VCU_PLL_CTRL_RESET_SHIFT;
+	xvcu_write(base, VCU_PLL_CTRL, vcu_pll_ctrl);
 
 	ret = xvcu_pll_wait_for_lock(xvcu);
 	if (ret) {
@@ -368,6 +366,18 @@ static int xvcu_pll_enable(struct xvcu_device *xvcu)
 
 static void xvcu_pll_disable(struct xvcu_device *xvcu)
 {
+	void __iomem *base = xvcu->vcu_slcr_ba;
+	u32 vcu_pll_ctrl;
+
+	vcu_pll_ctrl = xvcu_read(base, VCU_PLL_CTRL);
+	vcu_pll_ctrl &= ~(VCU_PLL_CTRL_POR_IN_MASK << VCU_PLL_CTRL_POR_IN_SHIFT);
+	vcu_pll_ctrl |= (1 & VCU_PLL_CTRL_POR_IN_MASK) << VCU_PLL_CTRL_POR_IN_SHIFT;
+	vcu_pll_ctrl &= ~(VCU_PLL_CTRL_PWR_POR_MASK << VCU_PLL_CTRL_PWR_POR_SHIFT);
+	vcu_pll_ctrl |= (1 & VCU_PLL_CTRL_PWR_POR_MASK) << VCU_PLL_CTRL_PWR_POR_SHIFT;
+	vcu_pll_ctrl &= ~(VCU_PLL_CTRL_RESET_MASK << VCU_PLL_CTRL_RESET_SHIFT);
+	vcu_pll_ctrl |= (1 & VCU_PLL_CTRL_RESET_MASK) << VCU_PLL_CTRL_RESET_SHIFT;
+	xvcu_write(base, VCU_PLL_CTRL, vcu_pll_ctrl);
+
 	clk_disable_unprepare(xvcu->pll_ref);
 }