ARM: imx: enable RBC to support anatop LPM mode

RBC is to control whether some ANATOP sub modules
can enter lpm mode when SOC is into STOP mode, if
RBC is enabled and PMIC_VSTBY_REQ is set, ANATOP
will have below behaviors:

1. Digital LDOs(CORE, SOC and PU) are bypassed;
2. Analog LDOs(1P1, 2P5, 3P0) are disabled;

As the 2P5 is necessary for DRAM IO pre-drive in
STOP mode, so we need to enable weak 2P5 in STOP
mode when 2P5 LDO is disabled.

For RBC settings, there are some rules as below
due to hardware design:

1. All interrupts must be masked during operating
   RBC registers;
2. At least 2 CKIL(32K) cycles is needed after the
   RBC setting is changed.

Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
index 262b7b6c79aa..23b799a51e6c 100644
--- a/arch/arm/mach-imx/clk-imx6q.c
+++ b/arch/arm/mach-imx/clk-imx6q.c
@@ -14,6 +14,7 @@
 #include <linux/types.h>
 #include <linux/clk.h>
 #include <linux/clkdev.h>
+#include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/of.h>
@@ -25,6 +26,8 @@
 
 #define CCR				0x0
 #define BM_CCR_WB_COUNT			(0x7 << 16)
+#define BM_CCR_RBC_BYPASS_COUNT		(0x3f << 21)
+#define BM_CCR_RBC_EN			(0x1 << 27)
 
 #define CCGR0				0x68
 #define CCGR1				0x6c
@@ -70,6 +73,44 @@ void imx6q_set_chicken_bit(void)
 	writel_relaxed(val, ccm_base + CGPR);
 }
 
+static void imx6q_enable_rbc(bool enable)
+{
+	u32 val;
+	static bool last_rbc_mode;
+
+	if (last_rbc_mode == enable)
+		return;
+	/*
+	 * need to mask all interrupts in GPC before
+	 * operating RBC configurations
+	 */
+	imx_gpc_mask_all();
+
+	/* configure RBC enable bit */
+	val = readl_relaxed(ccm_base + CCR);
+	val &= ~BM_CCR_RBC_EN;
+	val |= enable ? BM_CCR_RBC_EN : 0;
+	writel_relaxed(val, ccm_base + CCR);
+
+	/* configure RBC count */
+	val = readl_relaxed(ccm_base + CCR);
+	val &= ~BM_CCR_RBC_BYPASS_COUNT;
+	val |= enable ? BM_CCR_RBC_BYPASS_COUNT : 0;
+	writel(val, ccm_base + CCR);
+
+	/*
+	 * need to delay at least 2 cycles of CKIL(32K)
+	 * due to hardware design requirement, which is
+	 * ~61us, here we use 65us for safe
+	 */
+	udelay(65);
+
+	/* restore GPC interrupt mask settings */
+	imx_gpc_restore_all();
+
+	last_rbc_mode = enable;
+}
+
 static void imx6q_enable_wb(bool enable)
 {
 	u32 val;
@@ -101,6 +142,7 @@ int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode)
 	switch (mode) {
 	case WAIT_CLOCKED:
 		imx6q_enable_wb(false);
+		imx6q_enable_rbc(false);
 		break;
 	case WAIT_UNCLOCKED:
 		val |= 0x1 << BP_CLPCR_LPM;
@@ -120,6 +162,7 @@ int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode)
 		val |= BM_CLPCR_VSTBY;
 		val |= BM_CLPCR_SBYOS;
 		imx6q_enable_wb(true);
+		imx6q_enable_rbc(true);
 		break;
 	default:
 		return -EINVAL;