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mtd: rawnand: qcom: set BAM mode only if not set already

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BAM is DMA controller on QCOM ipq platforms, BAM mode on NAND driver
is set by writing BAM_MODE_EN bit on NAND_CTRL register.

NAND_CTRL is an operational register and in BAM mode operational
registers are read only.

So, before enabling BAM mode by writing the NAND_CTRL register, check
if BAM mode was already enabled by the bootloader, and enable BAM mode
only if it is not enabled already.

Signed-off-by: Sivaprakash Murugesan <sivaprak@codeaurora.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/1591948696-16015-3-git-send-email-sivaprak@codeaurora.org
This commit is contained in:
Sivaprakash Murugesan 2020-06-12 13:28:16 +05:30 committed by Miquel Raynal
parent 443440cc4a
commit cb272395dc
1 changed files with 10 additions and 1 deletions
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11
drivers/mtd/nand/raw/qcom_nandc.c
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@ -2784,7 +2784,16 @@ static int qcom_nandc_setup(struct qcom_nand_controller *nandc)
/* enable ADM or BAM DMA */
if (nandc->props->is_bam) {
nand_ctrl = nandc_read(nandc, NAND_CTRL);
nandc_write(nandc, NAND_CTRL, nand_ctrl | BAM_MODE_EN);
/*
*NAND_CTRL is an operational registers, and CPU
* access to operational registers are read only
* in BAM mode. So update the NAND_CTRL register
* only if it is not in BAM mode. In most cases BAM
* mode will be enabled in bootloader
*/
if (!(nand_ctrl & BAM_MODE_EN))
nandc_write(nandc, NAND_CTRL, nand_ctrl | BAM_MODE_EN);
} else {
nandc_write(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);
}