clk: imx: imx8mm: 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 clock

Fixes: ba5625c3e272 ("clk: imx: Add clock driver support for imx8mm")
Reviewed-by: Jacky Bai <[e-mail]>
Signed-off-by: Peng Fan <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

drivers/clk/imx/clk-imx8mm.c

···
 static const char *imx8mm_a53_sels[] = {"osc_24m", "arm_pll_out", "sys_pll2_500m", "sys_pll2_1000m",
 					"sys_pll1_800m", "sys_pll1_400m", "audio_pll1_out", "sys_pll3_out", };
 
+static const char * const imx8mm_a53_core_sels[] = {"arm_a53_div", "arm_pll_out", };
+
 static const char *imx8mm_m4_sels[] = {"osc_24m", "sys_pll2_200m", "sys_pll2_250m", "sys_pll1_266m",
 				       "sys_pll1_800m", "audio_pll1_out", "video_pll1_out", "sys_pll3_out", };
 
···
 	hws[IMX8MM_CLK_GPU2D_CG] = hws[IMX8MM_CLK_GPU2D_CORE];
 	hws[IMX8MM_CLK_GPU2D_DIV] = hws[IMX8MM_CLK_GPU2D_CORE];
 
+	/* CORE SEL */
+	hws[IMX8MM_CLK_A53_CORE] = imx_clk_hw_mux2_flags("arm_a53_core", base + 0x9880, 24, 1, imx8mm_a53_core_sels, ARRAY_SIZE(imx8mm_a53_core_sels), CLK_IS_CRITICAL);
+
 	/* BUS */
 	hws[IMX8MM_CLK_MAIN_AXI] = imx8m_clk_hw_composite_critical("main_axi",  imx8mm_main_axi_sels, base + 0x8800);
 	hws[IMX8MM_CLK_ENET_AXI] = imx8m_clk_hw_composite("enet_axi", imx8mm_enet_axi_sels, base + 0x8880);
···
 	hws[IMX8MM_CLK_DRAM_ALT_ROOT] = imx_clk_hw_fixed_factor("dram_alt_root", "dram_alt", 1, 4);
 	hws[IMX8MM_CLK_DRAM_CORE] = imx_clk_hw_mux2_flags("dram_core_clk", base + 0x9800, 24, 1, imx8mm_dram_core_sels, ARRAY_SIZE(imx8mm_dram_core_sels), CLK_IS_CRITICAL);
 
-	hws[IMX8MM_CLK_ARM] = imx_clk_hw_cpu("arm", "arm_a53_div",
-					   hws[IMX8MM_CLK_A53_DIV]->clk,
-					   hws[IMX8MM_CLK_A53_SRC]->clk,
+	clk_hw_set_parent(hws[IMX8MM_CLK_A53_SRC], hws[IMX8MM_SYS_PLL1_800M]);
+	clk_hw_set_parent(hws[IMX8MM_CLK_A53_CORE], hws[IMX8MM_ARM_PLL_OUT]);
+
+	hws[IMX8MM_CLK_ARM] = imx_clk_hw_cpu("arm", "arm_a53_core",
+					   hws[IMX8MM_CLK_A53_CORE]->clk,
+					   hws[IMX8MM_CLK_A53_CORE]->clk,
 					   hws[IMX8MM_ARM_PLL_OUT]->clk,
-					   hws[IMX8MM_SYS_PLL1_800M]->clk);
+					   hws[IMX8MM_CLK_A53_DIV]->clk);
 
 	imx_check_clk_hws(hws, IMX8MM_CLK_END);
 

include/dt-bindings/clock/imx8mm-clock.h

···
 
 #define IMX8MM_CLK_CLKO2			250
 
-#define IMX8MM_CLK_END				251
+#define IMX8MM_CLK_A53_CORE			251
+
+#define IMX8MM_CLK_END				252
 
 #endif