Re: [PATCH v5 10/23] clk: starfive: Add JHB100 System-2 clock generator driver

Hi, Brain

Thanks for the review.

Hi Changhuang,

On Wed, Sep 30, 2026 at 05:43:04AM -0700, Changhuang Liang wrote:

quoted

Add support for JHB100 System-2 clock generator (SYS2CRG).

Signed-off-by: Changhuang Liang <changhuang.liang@starfivetech.com>
---
 drivers/clk/starfive/Kconfig                  |  10 ++
 drivers/clk/starfive/Makefile                 |   1 +
 .../clk/starfive/clk-starfive-jhb100-sys2.c   | 129 ++++++++++++++++++
 3 files changed, 140 insertions(+)
 create mode 100644 drivers/clk/starfive/clk-starfive-jhb100-sys2.c

diff --git a/drivers/clk/starfive/Kconfig

b/drivers/clk/starfive/Kconfig index 11da8bcc4046..cfaac934a8e0 100644

--- a/drivers/clk/starfive/Kconfig
+++ b/drivers/clk/starfive/Kconfig

@@ -92,3 +92,13 @@ config CLK_STARFIVE_JHB100_SYS1
 	help
 	  Say yes here to support the system-1 clock controller on the
 	  StarFive JHB100 SoC.
+
+config CLK_STARFIVE_JHB100_SYS2
+	bool "StarFive JHB100 system-2 clock support"
+	depends on ARCH_STARFIVE || COMPILE_TEST
+	select CLK_STARFIVE_JH71X0
+	select RESET_STARFIVE_JHB100 if RESET_CONTROLLER
+	default ARCH_STARFIVE
+	help
+	  Say yes here to support the system-2 clock controller on the
+	  StarFive JHB100 SoC.

diff --git a/drivers/clk/starfive/Makefile

b/drivers/clk/starfive/Makefile index 0061550e0f7e..29cdef20575e
100644

--- a/drivers/clk/starfive/Makefile
+++ b/drivers/clk/starfive/Makefile

@@ -13,3 +13,4 @@ obj-$(CONFIG_CLK_STARFIVE_JH7110_VOUT)	+=

clk-starfive-jh7110-vout.o

quoted

 obj-$(CONFIG_CLK_STARFIVE_JHB100_SYS0)		+=

clk-starfive-jhb100-sys0.o

quoted

 obj-$(CONFIG_CLK_STARFIVE_JHB100_SYS1)		+=

clk-starfive-jhb100-sys1.o

quoted

+obj-$(CONFIG_CLK_STARFIVE_JHB100_SYS2)		+=

clk-starfive-jhb100-sys2.o

quoted

diff --git a/drivers/clk/starfive/clk-starfive-jhb100-sys2.c

b/drivers/clk/starfive/clk-starfive-jhb100-sys2.c
new file mode 100644
index 000000000000..a2c7e8eba9b6

--- /dev/null
+++ b/drivers/clk/starfive/clk-starfive-jhb100-sys2.c

@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * StarFive JHB100 System-2 Clock Driver
+ *
+ * Copyright (C) 2024 StarFive Technology Co., Ltd.
+ *
+ * Author: Changhuang Liang <changhuang.liang@starfivetech.com>
+ *
+ */
+
+#include <dt-bindings/clock/starfive,jhb100-crg.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+
+#include "clk-starfive-jh71x0.h"
+
+#define JHB100_SYS2CLK_NUM_CLKS

	(JHB100_SYS2CLK_MAIN_ICG_EN_JTAG1 + 1)

quoted

+
+/* external clocks */
+#define JHB100_SYS2CLK_OSC

	(JHB100_SYS2CLK_NUM_CLKS + 0)

quoted

+#define JHB100_SYS2CLK_PLL1

	(JHB100_SYS2CLK_NUM_CLKS + 1)

quoted

+#define JHB100_SYS2CLK_GPU0_NCNOC_INIT

	(JHB100_SYS2CLK_NUM_CLKS + 2)

quoted

+#define JHB100_SYS2CLK_GPU1_NCNOC_INIT

	(JHB100_SYS2CLK_NUM_CLKS + 3)

quoted

+
+static const char * const jhb100_sys2_ext_clk[] = {
+	"osc",
+	"pll1",
+	"gpu0_ncnoc_init",
+	"gpu1_ncnoc_init",
+};
+
+static const struct jh71x0_clk_data jhb100_sys2crg_clk_data[] = {
+	/* jtag mst*/
+	JH71X0__DIV(JHB100_SYS2CLK_JTAGM0_HCLK, "jtagm0_hclk", 6,
+		    JHB100_SYS2CLK_PLL1),
+	JH71X0__DIV(JHB100_SYS2CLK_JTAGM1_HCLK, "jtagm1_hclk", 6,
+		    JHB100_SYS2CLK_PLL1),
+	JH71X0__DIV(JHB100_SYS2CLK_JTAGM0_ATPG, "jtagm0_ATPG", 12,
+		    JHB100_SYS2CLK_PLL1),
+	JH71X0__DIV(JHB100_SYS2CLK_JTAGM1_ATPG, "jtagm1_ATPG", 12,
+		    JHB100_SYS2CLK_PLL1),
+	JH71X0__DIV(JHB100_SYS2CLK_JTAGM0_ATPG_TCLOCK,

"jtagm0_atpg_tclock", 2,

quoted

+		    JHB100_SYS2CLK_JTAGM0_ATPG),
+	JH71X0__DIV(JHB100_SYS2CLK_JTAGM1_ATPG_TCLOCK,

"jtagm1_atpg_tclock", 2,

quoted

+		    JHB100_SYS2CLK_JTAGM1_ATPG),
+	JH71X0_GATE(JHB100_SYS2CLK_JTAG0_MST_WRAP_HCLK,

"jtag0_mst_wrap_hclk",

quoted

+		    CLK_IGNORE_UNUSED, JHB100_SYS2CLK_JTAGM0_HCLK),

Can you leave a comment somewhere about why CLK_IGNORE_UNUSED is
on some of these clocks? We may be able to deprecate this flag once some
variation of the clk sync_state support lands:

https://lore.kernel.org/linux-clk/20260626-clk-sync-state-v1-0-4156d8196dc
8@redhat.com/

There are some clocks that we do not consume through a driver. Currently, 
CLK_IGNORE_UNUSED can keep them in their hardware default state (always on). 
If there is an intention to deprecate this flag, in the next version I may need to 
replace it with CLK_IS_CRITICAL.

quoted

+	JH71X0_GATE(JHB100_SYS2CLK_JTAG0_MST_WRAP_CLK_JTAG,

"jtag0_mst_wrap_clk_jtag",

quoted

+		    CLK_IGNORE_UNUSED, JHB100_SYS2CLK_JTAGM0_HCLK),
+	JH71X0_GATE(JHB100_SYS2CLK_JTAG0_MST_WRAP_APB_PCLK,

"jtag0_mst_wrap_apb_pclk",

quoted

+		    CLK_IGNORE_UNUSED, JHB100_SYS2CLK_JTAGM0_ATPG),
+	JH71X0_GATE(JHB100_SYS2CLK_JTAG0_MST_WRAP_ATPG_TCLOCK,

"jtag0_mst_wrap_atpg_tclock",

quoted

+		    CLK_IGNORE_UNUSED, JHB100_SYS2CLK_JTAGM0_ATPG),
+	JH71X0_GATE(JHB100_SYS2CLK_JTAG1_MST_WRAP_HCLK,

"jtag1_mst_wrap_hclk",

quoted

+		    CLK_IGNORE_UNUSED, JHB100_SYS2CLK_JTAGM1_HCLK),
+	JH71X0_GATE(JHB100_SYS2CLK_JTAG1_MST_WRAP_CLK_JTAG,

"jtag1_mst_wrap_clk_jtag",

quoted

+		    CLK_IGNORE_UNUSED, JHB100_SYS2CLK_JTAGM1_HCLK),
+	JH71X0_GATE(JHB100_SYS2CLK_JTAG1_MST_WRAP_APB_PCLK,

"jtag1_mst_wrap_apb_pclk",

quoted

+		    CLK_IGNORE_UNUSED, JHB100_SYS2CLK_JTAGM1_ATPG),
+	JH71X0_GATE(JHB100_SYS2CLK_JTAG1_MST_WRAP_ATPG_TCLOCK,

"jtag1_mst_wrap_atpg_tclock",

quoted

+		    CLK_IGNORE_UNUSED, JHB100_SYS2CLK_JTAGM1_ATPG),
+	/* hostusbcmn */
+	JH71X0__DIV(JHB100_SYS2CLK_HOSTUSB_NCNOC_TARG,

"hostusb_ncnoc_targ", 12,

quoted

+		    JHB100_SYS2CLK_PLL1),
+	JH71X0__DIV(JHB100_SYS2CLK_HOSTUSBCMN_CFG_500,

"hostusbcmn_cfg_500", 4,

quoted

+		    JHB100_SYS2CLK_PLL1),
+	/* bmcperiph1 */
+	JH71X0__DIV(JHB100_SYS2CLK_BMCPER1_NCNOC_TARG,

"bmcper1_ncnoc_targ", 6,

quoted

+		    JHB100_SYS2CLK_PLL1),
+	JH71X0__DIV(JHB100_SYS2CLK_BMCPER1_CFG_250,

"bmcper1_cfg_250", 5,

quoted

+		    JHB100_SYS2CLK_PLL1),
+	JH71X0__DIV(JHB100_SYS2CLK_BMCPER1_CFG_143_DFT,

"bmcper1_cfg_143_dft", 8,

quoted

+		    JHB100_SYS2CLK_PLL1),
+	JH71X0_GATE(JHB100_SYS2CLK_BMCPER1_CFG_143,

"bmcper1_cfg_143",

quoted

+CLK_IS_CRITICAL,

Also please leave a comment why CLK_IS_CRITICAL is needed as well for
these particular clocks.

OK.

Best Regards,
Changhuang