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 <Anson.Huang@xxxxxxx>
---
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(-)
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 <aisheng.dong@xxxxxxx>
*/
+#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
--
2.7.4
