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Md Sadre AlamandVinod Koul
867621ba20
BAM version 1.6.0 and later changed the behavior of the mask field in
command elements for read operations.
In older BAM versions, or prior implementation assumptions, the mask
field was effectively ignored for read commands. However, starting from
BAM v1.6.0, the mask field for read commands is repurposed to carry the
upper 4 bits of the destination address, enabling support for 36-bit
addressing. For write commands, the mask field continues to function as
a traditional write mask.
The current driver sets mask = 0xffffffff for all command elements.
While this works for write operations, it breaks read operations on
BAM v1.6.0+ hardware. In such cases, the hardware interprets the upper
address bits as 0xf, resulting in an invalid destination address
(0xf_xxxxxxxx instead of 0x0_xxxxxxxx).
This leads to failures such as NAND enumeration issues observed on
platforms like IPQ5424.
Fix this by assigning the mask field based on command type:
- For read commands: set mask = 0 (upper address bits = 0)
- For write commands: retain mask = 0xffffffff
Also update the bam_cmd_element structure documentation to reflect the
dual purpose of the mask field across BAM versions.
This ensures correct behavior on BAM v1.6.0+ while maintaining backward
compatibility with older hardware.
Fixes: dfebb055f7 ("dmaengine: qcom: bam_dma: wrapper functions for command descriptor")
Tested-by: Lakshmi Sowjanya D <lakshmi.d@oss.qualcomm.com>
Signed-off-by: Md Sadre Alam <md.alam@oss.qualcomm.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Varadarajan Narayanan <varadarajan.narayanan@oss.qualcomm.com>
Link: https://patch.msgid.link/20260615060908.1263171-1-varadarajan.narayanan@oss.qualcomm.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (c) 2016-2017, The Linux Foundation. All rights reserved.
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*/
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#ifndef _QCOM_BAM_DMA_H
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#define _QCOM_BAM_DMA_H
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#include <asm/byteorder.h>
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/*
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* This data type corresponds to the native Command Element
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* supported by BAM DMA Engine.
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*
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* @cmd_and_addr - upper 8 bits command and lower 24 bits register address.
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* @data - For write command: content to be written into peripheral register.
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* For read command: lower 32 bits of destination address.
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* @mask - For write command: register write mask.
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* For read command on BAM v1.6.0+: upper 4 bits of destination address.
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* For read command on BAM < v1.6.0: ignored by hardware.
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* Setting to 0 ensures 32-bit addressing compatibility.
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* @reserved - for future usage.
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*
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*/
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struct bam_cmd_element {
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__le32 cmd_and_addr;
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__le32 data;
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__le32 mask;
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__le32 reserved;
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};
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/*
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* This enum indicates the command type in a command element
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*/
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enum bam_command_type {
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BAM_WRITE_COMMAND = 0,
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BAM_READ_COMMAND,
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};
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/*
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* prep_bam_ce_le32 - Wrapper function to prepare a single BAM command
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* element with the data already in le32 format.
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*
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* @bam_ce: bam command element
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* @addr: target address
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* @cmd: BAM command
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* @data: actual data for write and dest addr for read in le32
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*
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* For BAM v1.6.0+, the mask field behavior depends on command type:
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* - Write commands: mask = write mask (typically 0xffffffff)
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* - Read commands: mask = upper 4 bits of destination address (0 for 32-bit)
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*/
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static inline void
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bam_prep_ce_le32(struct bam_cmd_element *bam_ce, u32 addr,
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enum bam_command_type cmd, __le32 data)
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{
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bam_ce->cmd_and_addr =
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cpu_to_le32((addr & 0xffffff) | ((cmd & 0xff) << 24));
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bam_ce->data = data;
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if (cmd == BAM_READ_COMMAND)
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bam_ce->mask = cpu_to_le32(0x0); /* 32-bit addressing */
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else
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bam_ce->mask = cpu_to_le32(0xffffffff); /* Write mask */
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bam_ce->reserved = 0;
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}
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/*
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* bam_prep_ce - Wrapper function to prepare a single BAM command element
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* with the data.
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*
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* @bam_ce: BAM command element
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* @addr: target address
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* @cmd: BAM command
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* @data: actual data for write and destination address for read
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*/
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static inline void
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bam_prep_ce(struct bam_cmd_element *bam_ce, u32 addr,
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enum bam_command_type cmd, u32 data)
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{
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bam_prep_ce_le32(bam_ce, addr, cmd, cpu_to_le32(data));
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}
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#endif
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