ARM: DRA7: Add support for IO delay configuration

On DRA7, in addition to the regular muxing of pins, an additional
hardware module called IODelay which is also expected to be
configured. This "IODelay" module has it's own register space that is
independent of the control module.

It is advocated strongly in TI's official documentation considering
the existing design of the DRA7 family of processors during mux or
IODelay recalibration, there is a potential for a significant glitch
which may cause functional impairment to certain hardware. It is
hence recommended to do muxing as part of IOdelay recalibration.

IODELAY recalibration sequence:
- Complete AVS voltage change on VDD_CORE_L
- Unlock IODLAY config registers.
- Perform IO delay calibration with predefined values.
- Isolate all the IOs
- Update the delay mechanism for each IO with new calibrated values.
- Configure PAD configuration registers
- De-isolate all the IOs.
- Relock IODELAY config registers.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>

3 files changed, 143 insertions, 0 deletions

diff --git a/arch/arm/cpu/armv7/omap5/Makefile b/arch/arm/cpu/armv7/omap5/Makefile
index 64c6879..e709f14 100644
--- a/arch/arm/cpu/armv7/omap5/Makefile
+++ b/arch/arm/cpu/armv7/omap5/Makefile
@@ -11,3 +11,4 @@ obj-y	+= sdram.o
 obj-y	+= prcm-regs.o
 obj-y	+= hw_data.o
 obj-y	+= abb.o
+obj-$(CONFIG_IODELAY_RECALIBRATION) += dra7xx_iodelay.o
diff --git a/arch/arm/cpu/armv7/omap5/dra7xx_iodelay.c b/arch/arm/cpu/armv7/omap5/dra7xx_iodelay.c
new file mode 100644
index 0000000..4b8ba26
--- /dev/null
+++ b/arch/arm/cpu/armv7/omap5/dra7xx_iodelay.c
@@ -0,0 +1,139 @@
+/*
+ * (C) Copyright 2015
+ * Texas Instruments Incorporated, <www.ti.com>
+ *
+ * Lokesh Vutla <lokeshvutla@ti.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <asm/utils.h>
+#include <asm/arch/dra7xx_iodelay.h>
+#include <asm/arch/omap.h>
+#include <asm/arch/sys_proto.h>
+#include <asm/arch/clock.h>
+#include <asm/omap_common.h>
+
+static int isolate_io(u32 isolate)
+{
+	if (isolate) {
+		clrsetbits_le32((*ctrl)->control_pbias, SDCARD_PWRDNZ,
+				SDCARD_PWRDNZ);
+		clrsetbits_le32((*ctrl)->control_pbias, SDCARD_BIAS_PWRDNZ,
+				SDCARD_BIAS_PWRDNZ);
+	}
+
+	/* Override control on ISOCLKIN signal to IO pad ring. */
+	clrsetbits_le32((*prcm)->prm_io_pmctrl, PMCTRL_ISOCLK_OVERRIDE_MASK,
+			PMCTRL_ISOCLK_OVERRIDE_CTRL);
+	if (!wait_on_value(PMCTRL_ISOCLK_STATUS_MASK, PMCTRL_ISOCLK_STATUS_MASK,
+			   (u32 *)(*prcm)->prm_io_pmctrl, LDELAY))
+		return ERR_DEISOLATE_IO << isolate;
+
+	/* Isolate/Deisolate IO */
+	clrsetbits_le32((*ctrl)->ctrl_core_sma_sw_0, CTRL_ISOLATE_MASK,
+			isolate << CTRL_ISOLATE_SHIFT);
+	/* Dummy read to add delay t > 10ns */
+	readl((*ctrl)->ctrl_core_sma_sw_0);
+
+	/* Return control on ISOCLKIN to hardware */
+	clrsetbits_le32((*prcm)->prm_io_pmctrl, PMCTRL_ISOCLK_OVERRIDE_MASK,
+			PMCTRL_ISOCLK_NOT_OVERRIDE_CTRL);
+	if (!wait_on_value(PMCTRL_ISOCLK_STATUS_MASK,
+			   0 << PMCTRL_ISOCLK_STATUS_SHIFT,
+			   (u32 *)(*prcm)->prm_io_pmctrl, LDELAY))
+		return ERR_DEISOLATE_IO << isolate;
+
+	return 0;
+}
+
+static int calibrate_iodelay(u32 base)
+{
+	u32 reg;
+
+	/* Configure REFCLK period */
+	reg = readl(base + CFG_REG_2_OFFSET);
+	reg &= ~CFG_REG_REFCLK_PERIOD_MASK;
+	reg |= CFG_REG_REFCLK_PERIOD;
+	writel(reg, base + CFG_REG_2_OFFSET);
+
+	/* Initiate Calibration */
+	clrsetbits_le32(base + CFG_REG_0_OFFSET, CFG_REG_CALIB_STRT_MASK,
+			CFG_REG_CALIB_STRT << CFG_REG_CALIB_STRT_SHIFT);
+	if (!wait_on_value(CFG_REG_CALIB_STRT_MASK, CFG_REG_CALIB_END,
+			   (u32 *)(base + CFG_REG_0_OFFSET), LDELAY))
+		return ERR_CALIBRATE_IODELAY;
+
+	return 0;
+}
+
+static int update_delay_mechanism(u32 base)
+{
+	/* Initiate the reload of calibrated values. */
+	clrsetbits_le32(base + CFG_REG_0_OFFSET, CFG_REG_ROM_READ_MASK,
+			CFG_REG_ROM_READ_START);
+	if (!wait_on_value(CFG_REG_ROM_READ_MASK, CFG_REG_ROM_READ_END,
+			   (u32 *)(base + CFG_REG_0_OFFSET), LDELAY))
+		return ERR_UPDATE_DELAY;
+
+	return 0;
+}
+
+void __recalibrate_iodelay(struct pad_conf_entry const *pad, int npads)
+{
+	int ret = 0;
+
+	/* IO recalibration should be done only from SRAM */
+	if (OMAP_INIT_CONTEXT_SPL != omap_hw_init_context()) {
+		puts("IODELAY recalibration called from invalid context - use only from SPL in SRAM\n");
+		return;
+	}
+
+	/* unlock IODELAY CONFIG registers */
+	writel(CFG_IODELAY_UNLOCK_KEY, (*ctrl)->iodelay_config_base +
+	       CFG_REG_8_OFFSET);
+
+	ret = calibrate_iodelay((*ctrl)->iodelay_config_base);
+	if (ret)
+		goto err;
+
+	ret = isolate_io(ISOLATE_IO);
+	if (ret)
+		goto err;
+
+	ret = update_delay_mechanism((*ctrl)->iodelay_config_base);
+	if (ret)
+		goto err;
+
+	/* Configure Mux settings */
+	do_set_mux32((*ctrl)->control_padconf_core_base, pad, npads);
+
+	ret = isolate_io(DEISOLATE_IO);
+
+err:
+	/* lock IODELAY CONFIG registers */
+	writel(CFG_IODELAY_LOCK_KEY, (*ctrl)->iodelay_config_base +
+	       CFG_REG_8_OFFSET);
+	/*
+	 * UART cannot be used during IO recalibration sequence as IOs are in
+	 * isolation. So error handling and debug prints are done after
+	 * complete IO delay recalibration sequence
+	 */
+	switch (ret) {
+	case ERR_CALIBRATE_IODELAY:
+		puts("IODELAY: IO delay calibration sequence failed\n");
+		break;
+	case ERR_ISOLATE_IO:
+		puts("IODELAY: Isolation of Device IOs failed\n");
+		break;
+	case ERR_UPDATE_DELAY:
+		puts("IODELAY: Delay mechanism update with new calibrated values failed\n");
+		break;
+	case ERR_DEISOLATE_IO:
+		puts("IODELAY: De-isolation of Device IOs failed\n");
+		break;
+	default:
+		debug("IODELAY: IO delay recalibration successfully completed\n");
+	}
+}
diff --git a/arch/arm/cpu/armv7/omap5/prcm-regs.c b/arch/arm/cpu/armv7/omap5/prcm-regs.c
index f80d36d..0547037 100644
--- a/arch/arm/cpu/armv7/omap5/prcm-regs.c
+++ b/arch/arm/cpu/armv7/omap5/prcm-regs.c
@@ -378,6 +378,7 @@ struct omap_sys_ctrl_regs const dra7xx_ctrl = {
 	.control_status				= 0x4A002134,
 	.control_phy_power_usb			= 0x4A002370,
 	.control_phy_power_sata			= 0x4A002374,
+	.ctrl_core_sma_sw_0			= 0x4A0023FC,
 	.control_core_mac_id_0_lo		= 0x4A002514,
 	.control_core_mac_id_0_hi		= 0x4A002518,
 	.control_core_mac_id_1_lo		= 0x4A00251C,
@@ -457,6 +458,7 @@ struct omap_sys_ctrl_regs const dra7xx_ctrl = {
 	.control_efuse_3			= 0x4AE0C5D0,
 	.control_efuse_4			= 0x4AE0C5D4,
 	.control_efuse_13			= 0x4AE0C5F0,
+	.iodelay_config_base			= 0x4844A000,
 };
 
 struct prcm_regs const omap5_es2_prcm = {
@@ -976,6 +978,7 @@ struct prcm_regs const dra7xx_prcm = {
 	.prm_rstctrl				= 0x4ae07d00,
 	.prm_rstst				= 0x4ae07d04,
 	.prm_rsttime				= 0x4ae07d08,
+	.prm_io_pmctrl				= 0x4ae07d20,
 	.prm_vc_val_bypass			= 0x4ae07da0,
 	.prm_vc_cfg_i2c_mode			= 0x4ae07db4,
 	.prm_vc_cfg_i2c_clk			= 0x4ae07db8,