/*
* Enable the DMA channel
* ASSUMES All other configuration bits have been set
* as desired before this code is called
*/
void pl08x_enable_dmac_chan(unsigned int cnum)
{
void __iomem *cbase = pd.base + PL08X_OS_CHAN_BASE +
(cnum * PL08X_OS_CHAN);
unsigned int r = 0;
/*
* Do not access config register until channel shows as disabled
*/
while ((readl(pd.base + PL08X_OS_ENCHNS) & (1 << cnum))
& PL08X_MASK_ENCHNS);
/*
* Do not access config register until channel shows as inactive
*/
r = readl(cbase + PL08X_OS_CCFG);
while ((r & PL08X_MASK_ACTIVE) || (r & PL08X_MASK_CEN))
r = readl(cbase + PL08X_OS_CCFG);
writel(r | PL08X_MASK_CEN, cbase + PL08X_OS_CCFG);
mb();
}
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等到对应channel是disable状态了,再接下来去enable它,会更安全 |
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等到对应channel是inactive状态了,再接下来去enable它,会更安全 |