17.2 EMIF ECC Programming

The programming sequence to use the OCMC RAM ECC feature is:

1. Enable EMIF ECC by configuring the EMIF1_EN_ECC bit in the CTRL_WKUP_EMIF1_SDRAM_CONFIG_EXT register in the TDA2xx and TDA2ex Control Module Registers, as shown in Table 74.

Table 74. CTRL_WKUP_EMIF1_SDRAM_CONFIG_EXT

Address Offset	0x0 0044
Physical Address	0x4AE00 C144	Instance		CTRL_MODULE_WKUP__Core_Registers
Description
Type	RW

Bits	Field Name	Description	Type	Reset
31:18	Reserved		RO	0x0000
17	EMIF1_NARROW_ONLY	EMIF1 ECC can be enabled	RW	0
		0: ECC cannot be enabled
		1: ECC can be enabled
16	EMIF1_EN_ECC
15:14	EMIF1_REG_PHY_NUM_OF_SAMPLES		RW	0x0
13	EMIF1_REG_PHY_SEL_LOGIC		RW	0
12	EMIF1_REG_PHY_ALL_DQ_MPR_RD_RESP		RW	0
11:9	EMIF1_REG_PHY_OUTPUT_STATUS_SELECT		RW	0x0
8	EMIF1_DYNAMIC_PWRDN_ENABLE		RW	1
7	EMIF1_SDRAM_DISABLE_RESET		RW	0
6:5	EMIF1_PHY_RD_LOCAL_ODT		RW	0x0
4	EMIF1_STATIC_CMOSEN_ENABLE		RW	0
3	EMIF1_DFI_CLOCK_PHASE_CTRL		RW	0
2	EMIF1_EN_SLICE_2		RW	1
1	EMIF1_EN_SLICE_1		RW	1
0	EMIF1_EN_SLICE_0		RW	1

7-bit ECC is calculated over 32-bit data when in 32-bit DDR mode (reg_narrow_mode = 0). 6-bit ECC is calculated over 16-bit data when in 16-bit DDR mode (reg_narrow_mode = 1). The ECC is calculated for all accesses that are within the address ranges protected by ECC.

NOTE

Note that only EMIF1 supports ECC on TDA2xx and TDA2ex.

2. Set the address range for ECC operation. The address ranges are specified in the ECC Address Range 1 and ECC Address Range 2 registers shown in Table 75 and Table 76.

Table 75. EMIF_ECC_ADDRESS_RANGE_1 (0x114)⁽¹⁾⁽²⁾

Bits	Field Name	Description	Type	Reset
31:16	REG_ECC_END_ADDR_1	End caddress [31:16] for ECC address range 1. The other 16 LSBs are always 0xFFFF.	R/W	0x0
15:0	REG_ECC_STRT_ADDR_1	Start caddress [31:16] for ECC address range 1. The other 16 LSBs are always 0xFFFF.	R/W	0x0

(1) This register can only be written if lock_config_ctrl port is cleared to 0.

(2) The range is inclusive of the start and end addresses.

Table 76. EMIF_ECC_ADDRESS_RANGE_2 (0x118)⁽¹⁾⁽²⁾

Bits	Field Name	Description	Type	Reset
31:16	REG_ECC_END_ADDR_2	End caddress [31:16] for ECC address range 2. The other 16 LSBs are always 0xFFFF.	R/W	0x0
15:0	REG_ECC_STRT_ADDR_2	Start caddress [31:16] for ECC address range 2.The other 16 LSBs are always 0xFFFF.	R/W	0x0

(1) This register can only be written if lock_config_ctrl port is cleared to 0.

(2) The range is inclusive of the start and end addresses.

Example:

//EMIF_ECC_ADDRESS_RANGE_1 - 0x80000000 to 0x90000000 WR_MEM_32(0x4C000114, 0x0FFF0000); //EMIF_ECC_ADDRESS_RANGE_2 - 0x90000000 to 0xA0000000 WR_MEM_32(0x4C000118, 0x1FFF1000);

CAUTION

The EMIF ECC region should not overlap; this can lead to unexpected results.

3. Enable ECC on both ranges by writing to the EMIF_ECC_CTRL_REG register as shown in Table 77. This register needs to be programmed to enable ECC, enable the regions and to define whether the ECC needs to be done within the region or outside the region.
   Table 77 explains the value of various bit fields.

Table 77. EMIF_ECC_CTRL_REG (0x110)⁽¹⁾

Bits	Field Name	Description	Type	Reset
31	REG_ECC_EN	ECC enable	R/W	0x0
		0: ECC is disabled.
		1: ECC is enabled.
30	REG_ECC_ADDR_RGN_PROT	Setting this field to 1 and reg_ecc_en to a 1 will enable ECC calculation for accesses within the address ranges and disable ECC calculation for accesses outside the address ranges. The address ranges can be specified using the ECC Address Range 1 and 2 registers.	R/W	0x0
29:2	RESERVED	Reserved	R	0x0
1	REG_ECC_ADDR_RGN_2_EN	ECC address range 2 enable.	R/W	0x0
		0: ECC address range 2 is disabled.
		1: ECC address range 2 is enabled.
0	REG_ECC_ADDR_RGN_1_EN	ECC address range 1 enable.	R/W	0x0
		0: ECC address range 1 is disabled.
		1: ECC address range 1 is enabled.

(1) This register can only be written if lock_config_ctrl port is cleared to 0.

NOTE

In DDR3 mode, software must trigger PHY initialization and full-leveling/calibration after enabling ECC for the first time. The ECC can then be enabled/disabled for test purposes without triggering full-leveling.

NOTE

ECC enable bit in CTRL_WKUP_EMIF_SDRAM_CONFIG_EXT register should be set even if ECC feature is not used.

Example:

if (ENABLE_ECC) //ECC Enabled { HW_WR_REG32(SOC_CTRL_MODULE_WKUP_CORE_REGISTERS_BASE + CTRL_WKUP_EMIF1_SDRAM_CONFIG_EXT, 0x0001C127U); /* EMIF1_EN_ECC = 1 */ }

NOTE

EMIF must be set to non-interleaving mode so that the lower 2-GiB memory can be properly mapped to EMIF1 with ECC support and EMIF2 that doesn’t have ECC supported.

Example:

if (MEMMAP_2GB_NON_INTL_EMIFX2) { printf("Two EMIFs in non interleaved mode (2GB total)\n"); /* MA_LISA_MAP_i */ WR_MEM_32(0x482AF040, 0x80600100); WR_MEM_32(0x482AF044, 0xC0600200); /* DMM_LISA_MAP_i */ WR_MEM_32(0x4E000040, 0x80600100); WR_MEM_32(0x4E000044, 0xC0600200); }
4. Set the threshold for 1 bit error interrupt - optional.

Single bit errors are corrected by ECC logic. So user need not get worried about that. But in cases, when there are many single bit errors, this can potentially mean that something in the environment or the memory is not correct. Software may choose to be informed of such condition. For that purpose, EMIF controller provides means to interrupt when single bit error crosses a desired threshold. For details of the register, see Table 78.

Table 78. 1B_ECC_ERR_THRSH – 1-Bit ECC Error Threshold Register (0x0134)

Bits	Name	Description
31:24	REG_1B_ECC_ERR_THRSH	1-bit ECC error threshold. The EMIF will generate an interrupt when the 1-bit ECC error count is greater than this threshold. A value of 0 will disable the generation of interrupt.
23:16	RESERVED	RESERVED
15:0	REG_1B_ECC_ERR_WIN	1-bit ECC error window in number of refresh periods. The EMIF will generate an interrupt when the 1-bit ECC error count is equal to or greater than the threshold within this window. A value of 0 will disable the window. Refresh period is defined by reg_refresh_rate in SDRAM Refresh Control register.

5. Clear the error status - optional.

This is again an optional step. Before enabling/using ECC, it is a good programming practice to clear any stale ECC error status. Table 79 and Table 80 should be cleared by writing 0x1 to it.

Table 79. EMIF_1B_ECC_ERR_ADDR_LOG – 1-Bit ECC Error Address Log Register (0x013C)

Bits	Name	Description
31:0	REG_1B_ECC_ERR_ADDR	1-bit ECC error address. Most significant bits of the starting address(es) related to the SDRAM reads that had a 1-bit ECC error. This field displays up to two addresses logged in the 4 deep address logging FIFO. Writing a 0x1 will pop one element of the FIFO. Writing a 0x2 will pop all elements of the FIFO. Writing any other value has no effect.

Table 80. EMIF_2B_ECC_ERR_ADDR_LOG – 2-Bit ECC Error Address Log Register (0x0140)

Bits	Name	Description
31:0	REG_2B_ECC_ERR_ADDR	2-bit ECC error address. Most significant bits of the starting address of the first SDRAM burst that had the 2-bit ECC error. Writing a 0x1 will clear this field. Writing any other value has no effect.

6. Enable the interrupts.

In order to receive interrupts, one should set the EMIF interrupt enable in the EMIF configuration space. The register description is shown in Table 81.

Table 81. EMIF_SYSTEM_OCP_INTERRUPT_ENABLE_SET (0x00b4)

Bits	Name	Description
31:6	Reserved	Reserved - writes are ignored, always reads zeros.
5	ONEBIT_ECC_ERR_SYS	Enabled status of sysem ECC one bit error correction interrupt. Writing a 1 will enable the interrupt, and set this bit as well as the corresponding Interrupt Enable Clear Register. Writing a 0 has no effect.
4	TWOBIT_ECC_ERR_SYS	Enabled status of system ECC two bit error detection interrupt. Writing a 1 will enable the interrupt, and set this bit as well as the corresponding Interrupt Enable Clear Register. Writing a 0 has no effect.
3	WR_ECC_ERR_SYS	Enabled status of system ECC Error interrupt when a memory access is made to a non-quanta aligned location. Writing a 1 will enable the interrupt, and set this bit as well as the corresponding Interrupt Enable Clear Register. Writing a 0 has no effect.
2-1	Reserved	Reserved
0	EN_ERR_SYS	Enable set for system OCP interrupt for command and address error. Writing a 1 will enable the interrupt, and set this bit as well as the corresponding Interrupt Enable Clear Register. Writing a 0 has no effect.

Also, the SoC crossbar should be configured properly to receive the EMIF interrupt to the desired CPU. For example, for A15, SYSBIOS, below code needs to be added in configuration file.

var IntXbar = xdc.useModule('ti.sysbios.family.shared.vayu.IntXbar'); var Hwi = xdc.useModule('ti.sysbios.family.arm.gic.Hwi'); /* IRQ_CROSSBAR_105 EMIF1_IRQ. Interrupt 57 on A15 */ IntXbar.connectIRQMeta(57, 105); var hwi_param_0 = new Hwi.Params; hwi_param_0.arg = 0; Hwi.create(57+32, '&emifErrIrqIsr', hwi_param_0);
7. Initialize ECC enabled memory regions. DDR initialization is needed so that the ECC checksum memory gets initialized properly. Given that the DDR and ECC parity bits are uninitialized when the device is first powered on, it is important for the software to first initialize the whole memory after enabling the ECC.
   1. This step ensures that the parity bits are correctly set before the code access to ECC enabled regions.
   2. This step ensures that ECC error scenarios are not generated for uninitialized parity data.
   3. This step can be done by either the CPU memset or the EDMA transfer to the memory region.
   4. The initialization requirement is multiple of 2 bytes for narrow_mode = 0, 4 bytes for narrow_mode = 1.
   5. When using an EDMA to initialize the memory, Care should be taken to ensure the start address and end address is 32- or 16-bit aligned (based on normal or narrow mode) when initializing.
8. ECC programming is now complete, resume normal operation of the code.

There are other steps related to the below that are not listed but can be used and present in software provided by TI:

• Disable ECC
• Clearing interrupts status
• Disabling interrupts
• Getting RAW status of error
• Getting ECC error info

For more description on how to do these, see the TI software.

Example: