[PATCH v2 1/2] ram: stm32mp1: Unconditionally enable ASR

[Marek Vasut <marex@denx.de>]

Enable DRAM ASR, auto self-refresh, unconditionally. This saves non-trivial
amount of power both at runtime and in suspend (on 2x W632GU6NB-15 ~150mW).

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Patrick Delaunay <patrick.delaunay@foss.st.com>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>
---
V2: Rebase on latest changes in this driver past v2022.01
---
 drivers/ram/stm32mp1/stm32mp1_ddr.c      | 25 ++++++++++++++++++++++++
 drivers/ram/stm32mp1/stm32mp1_ddr_regs.h |  6 ++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/ram/stm32mp1/stm32mp1_ddr.c b/drivers/ram/stm32mp1/stm32mp1_ddr.c
index 4d78aa5cb13..04fc8eab909 100644
--- a/drivers/ram/stm32mp1/stm32mp1_ddr.c
+++ b/drivers/ram/stm32mp1/stm32mp1_ddr.c
@@ -27,6 +27,8 @@
 #define RCC_DDRITFCR_DPHYAPBRST		(BIT(17))
 #define RCC_DDRITFCR_DPHYRST		(BIT(18))
 #define RCC_DDRITFCR_DPHYCTLRST		(BIT(19))
+#define RCC_DDRITFCR_DDRCKMOD_MASK	(0x7 << 20)
+#define RCC_DDRITFCR_DDRCKMOD_ASR	(0x1 << 20)
 
 struct reg_desc {
 	const char *name;
@@ -651,6 +653,26 @@ static void stm32mp1_refresh_restore(struct stm32mp1_ddrctl *ctl,
 	wait_sw_done_ack(ctl);
 }
 
+static void stm32mp1_asr_enable(struct ddr_info *priv)
+{
+	struct stm32mp1_ddrctl *ctl = priv->ctl;
+
+	clrsetbits_le32(priv->rcc + RCC_DDRITFCR, RCC_DDRITFCR_DDRCKMOD_MASK,
+			RCC_DDRITFCR_DDRCKMOD_ASR);
+
+	start_sw_done(ctl);
+
+	setbits_le32(&ctl->hwlpctl, DDRCTRL_HWLPCTL_HW_LP_EN);
+	writel(DDRCTRL_PWRTMG_POWERDOWN_TO_X32(0x10) |
+	       DDRCTRL_PWRTMG_SELFREF_TO_X32(0x01),
+	       &ctl->pwrtmg);
+	setbits_le32(&ctl->pwrctl, DDRCTRL_PWRCTL_EN_DFI_DRAM_CLK_DISABLE);
+	setbits_le32(&ctl->pwrctl, DDRCTRL_PWRCTL_SELFREF_EN);
+
+	setbits_le32(&ctl->dfimisc, DDRCTRL_DFIMISC_DFI_INIT_COMPLETE_EN);
+	wait_sw_done_ack(ctl);
+}
+
 /* board-specific DDR power initializations. */
 __weak int board_ddr_power_init(enum ddr_type ddr_type)
 {
@@ -822,6 +844,9 @@ start:
 	stm32mp1_refresh_restore(priv->ctl, config->c_reg.rfshctl3,
 				 config->c_reg.pwrctl);
 
+/* Enable auto-self-refresh, which saves a bit of power at runtime. */
+	stm32mp1_asr_enable(priv);
+
 	/* enable uMCTL2 AXI port 0 and 1 */
 	setbits_le32(&priv->ctl->pctrl_0, DDRCTRL_PCTRL_N_PORT_EN);
 	setbits_le32(&priv->ctl->pctrl_1, DDRCTRL_PCTRL_N_PORT_EN);
diff --git a/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h b/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h
index f1a26e31f6c..42be1ba57c7 100644
--- a/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h
+++ b/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h
@@ -265,8 +265,14 @@ struct stm32mp1_ddrphy {
 
 #define DDRCTRL_PWRCTL_SELFREF_EN		BIT(0)
 #define DDRCTRL_PWRCTL_POWERDOWN_EN		BIT(1)
+#define DDRCTRL_PWRCTL_EN_DFI_DRAM_CLK_DISABLE	BIT(3)
 #define DDRCTRL_PWRCTL_SELFREF_SW		BIT(5)
 
+#define DDRCTRL_PWRTMG_SELFREF_TO_X32(n)	(((n) & 0xff) << 16)
+#define DDRCTRL_PWRTMG_POWERDOWN_TO_X32(n)	((n) & 0x1f)
+
+#define DDRCTRL_HWLPCTL_HW_LP_EN		BIT(0)
+
 #define DDRCTRL_RFSHCTL3_DIS_AUTO_REFRESH	BIT(0)
 
 #define DDRCTRL_RFSHTMG_T_RFC_NOM_X1_X32_MASK	GENMASK(27, 16)
-- 
2.34.1