clk: imx: imx8mn: fix a53 cpu clock

The A53 CCM clk root only accepts input up to 1GHz, CCM A53 root
signoff timing is 1Ghz, however the A53 core which sources from CCM
root could run above 1GHz which voilates the CCM.

There is a CORE_SEL slice before A53 core, we need configure the
CORE_SEL slice source from ARM PLL, not A53 CCM clk root.

The A53 CCM clk root should only be used when need to change ARM PLL
frequency.

Add arm_a53_core clk that could source from arm_a53_div and arm_pll_out.
Configure a53 ccm root sources from 800MHz sys pll
Configure a53 core sources from arm_pll_out
Mark arm_a53_core as critical clk.

Fixes: 96d6392b ("clk: imx: Add support for i.MX8MN clock driver")
Reviewed-by: Jacky Bai <ping.bai@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/clk/imx/clk-imx8mn.c

@@ -38,6 +38,8 @@ static const char * const imx8mn_a53_sels[] = {"osc_24m", "arm_pll_out", "sys_pl
 					       "sys_pll2_1000m", "sys_pll1_800m", "sys_pll1_400m",
 					       "audio_pll1_out", "sys_pll3_out", };
 
+static const char * const imx8mn_a53_core_sels[] = {"arm_a53_div", "arm_pll_out", };
+
 static const char * const imx8mn_gpu_core_sels[] = {"osc_24m", "gpu_pll_out", "sys_pll1_800m",
 						    "sys_pll3_out", "sys_pll2_1000m", "audio_pll1_out",
 						    "video_pll1_out", "audio_pll2_out", };
@@ -425,6 +427,9 @@ static int imx8mn_clocks_probe(struct platform_device *pdev)
 	hws[IMX8MN_CLK_GPU_SHADER_CG] = hws[IMX8MN_CLK_GPU_SHADER];
 	hws[IMX8MN_CLK_GPU_SHADER_DIV] = hws[IMX8MN_CLK_GPU_SHADER];
 
+	/* CORE SEL */
+	hws[IMX8MN_CLK_A53_CORE] = imx_clk_hw_mux2_flags("arm_a53_core", base + 0x9880, 24, 1, imx8mn_a53_core_sels, ARRAY_SIZE(imx8mn_a53_core_sels), CLK_IS_CRITICAL);
+
 	/* BUS */
 	hws[IMX8MN_CLK_MAIN_AXI] = imx8m_clk_hw_composite_critical("main_axi", imx8mn_main_axi_sels, base + 0x8800);
 	hws[IMX8MN_CLK_ENET_AXI] = imx8m_clk_hw_composite("enet_axi", imx8mn_enet_axi_sels, base + 0x8880);
@@ -554,11 +559,14 @@ static int imx8mn_clocks_probe(struct platform_device *pdev)
 
 	hws[IMX8MN_CLK_DRAM_ALT_ROOT] = imx_clk_hw_fixed_factor("dram_alt_root", "dram_alt", 1, 4);
 
-	hws[IMX8MN_CLK_ARM] = imx_clk_hw_cpu("arm", "arm_a53_div",
-					   hws[IMX8MN_CLK_A53_DIV]->clk,
-					   hws[IMX8MN_CLK_A53_SRC]->clk,
+	clk_hw_set_parent(hws[IMX8MN_CLK_A53_SRC], hws[IMX8MN_SYS_PLL1_800M]);
+	clk_hw_set_parent(hws[IMX8MN_CLK_A53_CORE], hws[IMX8MN_ARM_PLL_OUT]);
+
+	hws[IMX8MN_CLK_ARM] = imx_clk_hw_cpu("arm", "arm_a53_core",
+					   hws[IMX8MN_CLK_A53_CORE]->clk,
+					   hws[IMX8MN_CLK_A53_CORE]->clk,
 					   hws[IMX8MN_ARM_PLL_OUT]->clk,
-					   hws[IMX8MN_SYS_PLL1_800M]->clk);
+					   hws[IMX8MN_CLK_A53_DIV]->clk);
 
 	imx_check_clk_hws(hws, IMX8MN_CLK_END);
 

include/dt-bindings/clock/imx8mn-clock.h

@@ -232,6 +232,8 @@
 #define IMX8MN_CLK_GPU_CORE			212
 #define IMX8MN_CLK_GPU_SHADER			213
 
-#define IMX8MN_CLK_END				214
+#define IMX8MN_CLK_A53_CORE			214
+
+#define IMX8MN_CLK_END				215
 
 #endif