[SCSI] isci: enable clock gating

Enabling clock gating for power savings on entry to controller ready
state. Disable SCU clock gating for power savings on exit from the
controller ready state.

The gating is fully automated by silicon after setting the mode.
Signed-off-by: NMarcin Tomczak <marcin.tomczak@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/isci/host.c

@@ -1491,6 +1491,15 @@ sci_controller_set_interrupt_coalescence(struct isci_host *ihost,
 static void sci_controller_ready_state_enter(struct sci_base_state_machine *sm)
 {
 	struct isci_host *ihost = container_of(sm, typeof(*ihost), sm);
+	u32 val;
+
+	/* enable clock gating for power control of the scu unit */
+	val = readl(&ihost->smu_registers->clock_gating_control);
+	val &= ~(SMU_CGUCR_GEN_BIT(REGCLK_ENABLE) |
+		 SMU_CGUCR_GEN_BIT(TXCLK_ENABLE) |
+		 SMU_CGUCR_GEN_BIT(XCLK_ENABLE));
+	val |= SMU_CGUCR_GEN_BIT(IDLE_ENABLE);
+	writel(val, &ihost->smu_registers->clock_gating_control);
 
 	/* set the default interrupt coalescence number and timeout value. */
 	sci_controller_set_interrupt_coalescence(ihost, 0, 0);

drivers/scsi/isci/registers.h

@@ -370,6 +370,27 @@ struct scu_iit_entry {
 		>> SMU_DEVICE_CONTEXT_CAPACITY_MAX_RNC_SHIFT \
 	)
 
+/* ***************************************************************************** */
+#define SMU_CLOCK_GATING_CONTROL_IDLE_ENABLE_SHIFT    (0)
+#define SMU_CLOCK_GATING_CONTROL_IDLE_ENABLE_MASK     (0x00000001)
+#define SMU_CLOCK_GATING_CONTROL_XCLK_ENABLE_SHIFT    (1)
+#define SMU_CLOCK_GATING_CONTROL_XCLK_ENABLE_MASK     (0x00000002)
+#define SMU_CLOCK_GATING_CONTROL_TXCLK_ENABLE_SHIFT   (2)
+#define SMU_CLOCK_GATING_CONTROL_TXCLK_ENABLE_MASK    (0x00000004)
+#define SMU_CLOCK_GATING_CONTROL_REGCLK_ENABLE_SHIFT  (3)
+#define SMU_CLOCK_GATING_CONTROL_REGCLK_ENABLE_MASK   (0x00000008)
+#define SMU_CLOCK_GATING_CONTROL_IDLE_TIMEOUT_SHIFT   (16)
+#define SMU_CLOCK_GATING_CONTROL_IDLE_TIMEOUT_MASK    (0x000F0000)
+#define SMU_CLOCK_GATING_CONTROL_FORCE_IDLE_SHIFT     (31)
+#define SMU_CLOCK_GATING_CONTROL_FORCE_IDLE_MASK      (0x80000000)
+#define SMU_CLOCK_GATING_CONTROL_RESERVED_MASK        (0x7FF0FFF0)
+
+#define SMU_CGUCR_GEN_VAL(name, value) \
+	SCU_GEN_VALUE(SMU_CLOCK_GATING_CONTROL_##name, value)
+
+#define SMU_CGUCR_GEN_BIT(name) \
+	SCU_GEN_BIT(SMU_CLOCK_GATING_CONTROL_##name)
+
 /* -------------------------------------------------------------------------- */
 
 #define SMU_CONTROL_STATUS_TASK_CONTEXT_RANGE_ENABLE_SHIFT      (0)
@@ -992,8 +1013,10 @@ struct smu_registers {
 	u32 mmr_address_window;
 /* 0x00A4 SMDW */
 	u32 mmr_data_window;
-	u32 reserved_A8;
-	u32 reserved_AC;
+/* 0x00A8 CGUCR */
+	u32 clock_gating_control;
+/* 0x00AC CGUPC */
+	u32 clock_gating_performance;
 /* A whole bunch of reserved space */
 	u32 reserved_Bx[4];
 	u32 reserved_Cx[4];