[V4,2/2] clk: imx: scu: add cpu frequency scaling support

Commit Message

Anson Huang Feb. 14, 2019, 1:54 a.m. UTC

On NXP's i.MX SoCs with system controller inside, CPU frequency
scaling can ONLY be done by system controller firmware, and it
can ONLY be requested from secure mode, so Linux kernel has to
call ARM SMC to trap to ARM-Trusted-Firmware to request system
controller firmware to do CPU frequency scaling.

This patch adds i.MX system controller CPU frequency scaling support,
it reuses cpufreq-dt driver and implement the CPU frequency scaling
inside SCU clock driver.

Signed-off-by: Anson Huang <[e-mail]>
---
Changes since V3:
        - use different clk ops for CPU clock to avoid runtime check in clk_set_rate;
        - use rsrc_id to determine whether it is CPU frequency change and also to get
          cluster ID for SMC call.
---
 drivers/clk/imx/clk-scu.c | 35 ++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

Comments

Stephen Boyd Feb. 15, 2019, 11:58 p.m. UTC | #1

Quoting Anson Huang (2019-02-13 17:54:08)
> On NXP's i.MX SoCs with system controller inside, CPU frequency
> scaling can ONLY be done by system controller firmware, and it
> can ONLY be requested from secure mode, so Linux kernel has to
> call ARM SMC to trap to ARM-Trusted-Firmware to request system
> controller firmware to do CPU frequency scaling.
> 
> This patch adds i.MX system controller CPU frequency scaling support,
> it reuses cpufreq-dt driver and implement the CPU frequency scaling
> inside SCU clock driver.
> 
> Signed-off-by: Anson Huang <[e-mail]>
> ---

Acked-by: Stephen Boyd <[e-mail]>

Unless you wanted me to pick this patch up into clk-next?

Anson Huang Feb. 16, 2019, 12:41 a.m. UTC | #2

Hi, Stephen

Best Regards!
Anson Huang

> -----Original Message-----
> From: Stephen Boyd [mailto:[e-mail]]
> Sent: 2019年2月16日 7:58
> To: [e-mail]; [e-mail];
> [e-mail]; [e-mail]; linux-
> [e-mail]; [e-mail]; [e-mail];
> [e-mail]; [e-mail]; [e-mail];
> [e-mail]; [e-mail]; Aisheng Dong
> <[e-mail]>; Anson Huang <[e-mail]>; Daniel
> Baluta <[e-mail]>
> Cc: dl-linux-imx <[e-mail]>
> Subject: Re: [PATCH V4 2/2] clk: imx: scu: add cpu frequency scaling support
> 
> Quoting Anson Huang (2019-02-13 17:54:08)
> > On NXP's i.MX SoCs with system controller inside, CPU frequency
> > scaling can ONLY be done by system controller firmware, and it can
> > ONLY be requested from secure mode, so Linux kernel has to call ARM
> > SMC to trap to ARM-Trusted-Firmware to request system controller
> > firmware to do CPU frequency scaling.
> >
> > This patch adds i.MX system controller CPU frequency scaling support,
> > it reuses cpufreq-dt driver and implement the CPU frequency scaling
> > inside SCU clock driver.
> >
> > Signed-off-by: Anson Huang <[e-mail]>
> > ---
> 
> Acked-by: Stephen Boyd <[e-mail]>
> 
> Unless you wanted me to pick this patch up into clk-next?

Yes, please, we want to support cpu-freq scaling in Linux next tree ASAP.

Thanks,
Anson.

Stephen Boyd Feb. 21, 2019, 8:48 p.m. UTC | #3

Quoting Anson Huang (2019-02-13 17:54:08)
> On NXP's i.MX SoCs with system controller inside, CPU frequency
> scaling can ONLY be done by system controller firmware, and it
> can ONLY be requested from secure mode, so Linux kernel has to
> call ARM SMC to trap to ARM-Trusted-Firmware to request system
> controller firmware to do CPU frequency scaling.
> 
> This patch adds i.MX system controller CPU frequency scaling support,
> it reuses cpufreq-dt driver and implement the CPU frequency scaling
> inside SCU clock driver.
> 
> Signed-off-by: Anson Huang <[e-mail]>
> ---
> Changes since V3:
>         - use different clk ops for CPU clock to avoid runtime check in clk_set_rate;
>         - use rsrc_id to determine whether it is CPU frequency change and also to get
>           cluster ID for SMC call.

This directly conflicts with a patch to add get/set parent support from
Aisheng Dong. Can you please work together and rebase the patch on top
of that patch (which is in clk-next) and resend this?

Anson Huang Feb. 22, 2019, 2:34 a.m. UTC | #4

Hi, Stephen

Best Regards!
Anson Huang

> -----Original Message-----
> From: Stephen Boyd [mailto:[e-mail]]
> Sent: 2019年2月22日 4:48
> To: [e-mail]; [e-mail];
> [e-mail]; [e-mail]; linux-
> [e-mail]; [e-mail]; [e-mail];
> [e-mail]; [e-mail]; [e-mail];
> [e-mail]; [e-mail]; Aisheng Dong
> <[e-mail]>; Anson Huang <[e-mail]>; Daniel
> Baluta <[e-mail]>
> Cc: dl-linux-imx <[e-mail]>
> Subject: Re: [PATCH V4 2/2] clk: imx: scu: add cpu frequency scaling support
> 
> Quoting Anson Huang (2019-02-13 17:54:08)
> > On NXP's i.MX SoCs with system controller inside, CPU frequency
> > scaling can ONLY be done by system controller firmware, and it can
> > ONLY be requested from secure mode, so Linux kernel has to call ARM
> > SMC to trap to ARM-Trusted-Firmware to request system controller
> > firmware to do CPU frequency scaling.
> >
> > This patch adds i.MX system controller CPU frequency scaling support,
> > it reuses cpufreq-dt driver and implement the CPU frequency scaling
> > inside SCU clock driver.
> >
> > Signed-off-by: Anson Huang <[e-mail]>
> > ---
> > Changes since V3:
> >         - use different clk ops for CPU clock to avoid runtime check in
> clk_set_rate;
> >         - use rsrc_id to determine whether it is CPU frequency change and also
> to get
> >           cluster ID for SMC call.
> 
> This directly conflicts with a patch to add get/set parent support from
> Aisheng Dong. Can you please work together and rebase the patch on top of
> that patch (which is in clk-next) and resend this?

I have resent the patch set based on top of clk-next and tested the function.
Please apply this resent patch, https://patchwork.kernel.org/patch/10825085/

Thanks,
Anson.

Patch

diff --git a/drivers/clk/imx/clk-scu.c b/drivers/clk/imx/clk-scu.c
index 7ccf7ed..c234a6e 100644
--- a/drivers/clk/imx/clk-scu.c
+++ b/drivers/clk/imx/clk-scu.c
@@ -4,12 +4,17 @@ 
  *   Dong Aisheng <[e-mail]>
  */
 
+#include <dt-bindings/firmware/imx/rsrc.h>
+#include <linux/arm-smccc.h>
 #include <linux/clk-provider.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 
 #include "clk-scu.h"
 
+#define IMX_SIP_CPUFREQ			0xC2000001
+#define IMX_SIP_SET_CPUFREQ		0x00
+
 static struct imx_sc_ipc *ccm_ipc_handle;
 
 /*
@@ -145,6 +150,23 @@  static long clk_scu_round_rate(struct clk_hw *hw, unsigned long rate,
 	return rate;
 }
 
+static int clk_scu_atf_set_cpu_rate(struct clk_hw *hw, unsigned long rate,
+				    unsigned long parent_rate)
+{
+	struct clk_scu *clk = to_clk_scu(hw);
+	struct arm_smccc_res res;
+	unsigned long cluster_id;
+
+	if (clk->rsrc_id == IMX_SC_R_A35)
+		cluster_id = 0;
+
+	/* CPU frequency scaling can ONLY be done by ARM-Trusted-Firmware */
+	arm_smccc_smc(IMX_SIP_CPUFREQ, IMX_SIP_SET_CPUFREQ,
+		      cluster_id, rate, 0, 0, 0, 0, &res);
+
+	return 0;
+}
+
 /*
  * clk_scu_set_rate - Set rate for a SCU clock
  * @hw: clock to change rate for
@@ -232,6 +254,14 @@  static const struct clk_ops clk_scu_ops = {
 	.unprepare = clk_scu_unprepare,
 };
 
+static const struct clk_ops clk_scu_cpu_ops = {
+	.recalc_rate = clk_scu_recalc_rate,
+	.round_rate = clk_scu_round_rate,
+	.set_rate = clk_scu_atf_set_cpu_rate,
+	.prepare = clk_scu_prepare,
+	.unprepare = clk_scu_unprepare,
+};
+
 struct clk_hw *imx_clk_scu(const char *name, u32 rsrc_id, u8 clk_type)
 {
 	struct clk_init_data init;
@@ -247,7 +277,10 @@  struct clk_hw *imx_clk_scu(const char *name, u32 rsrc_id, u8 clk_type)
 	clk->clk_type = clk_type;
 
 	init.name = name;
-	init.ops = &clk_scu_ops;
+	if (rsrc_id == IMX_SC_R_A35)
+		init.ops = &clk_scu_cpu_ops;
+	else
+		init.ops = &clk_scu_ops;
 	init.num_parents = 0;
 	/*
 	 * Note on MX8, the clocks are tightly coupled with power domain