diff options
Diffstat (limited to 'arch/powerpc/sysdev/qe_lib/qe.c')
| -rw-r--r-- | arch/powerpc/sysdev/qe_lib/qe.c | 36 |
1 files changed, 23 insertions, 13 deletions
diff --git a/arch/powerpc/sysdev/qe_lib/qe.c b/arch/powerpc/sysdev/qe_lib/qe.c index 90f87408b5d..3d57d3835b0 100644 --- a/arch/powerpc/sysdev/qe_lib/qe.c +++ b/arch/powerpc/sysdev/qe_lib/qe.c @@ -141,7 +141,7 @@ EXPORT_SYMBOL(qe_issue_cmd); * 16 BRGs, which can be connected to the QE channels or output * as clocks. The BRGs are in two different block of internal * memory mapped space. - * The baud rate clock is the system clock divided by something. + * The BRG clock is the QE clock divided by 2. * It was set up long ago during the initial boot phase and is * is given to us. * Baud rate clocks are zero-based in the driver code (as that maps @@ -165,28 +165,38 @@ unsigned int get_brg_clk(void) return brg_clk; } -/* This function is used by UARTS, or anything else that uses a 16x - * oversampled clock. +/* Program the BRG to the given sampling rate and multiplier + * + * @brg: the BRG, 1-16 + * @rate: the desired sampling rate + * @multiplier: corresponds to the value programmed in GUMR_L[RDCR] or + * GUMR_L[TDCR]. E.g., if this BRG is the RX clock, and GUMR_L[RDCR]=01, + * then 'multiplier' should be 8. + * + * Also note that the value programmed into the BRGC register must be even. */ -void qe_setbrg(u32 brg, u32 rate) +void qe_setbrg(unsigned int brg, unsigned int rate, unsigned int multiplier) { - volatile u32 *bp; u32 divisor, tempval; - int div16 = 0; + u32 div16 = 0; - bp = &qe_immr->brg.brgc[brg]; + divisor = get_brg_clk() / (rate * multiplier); - divisor = (get_brg_clk() / rate); if (divisor > QE_BRGC_DIVISOR_MAX + 1) { - div16 = 1; + div16 = QE_BRGC_DIV16; divisor /= 16; } - tempval = ((divisor - 1) << QE_BRGC_DIVISOR_SHIFT) | QE_BRGC_ENABLE; - if (div16) - tempval |= QE_BRGC_DIV16; + /* Errata QE_General4, which affects some MPC832x and MPC836x SOCs, says + that the BRG divisor must be even if you're not using divide-by-16 + mode. */ + if (!div16 && (divisor & 1)) + divisor++; + + tempval = ((divisor - 1) << QE_BRGC_DIVISOR_SHIFT) | + QE_BRGC_ENABLE | div16; - out_be32(bp, tempval); + out_be32(&qe_immr->brg.brgc[brg - 1], tempval); } /* Initialize SNUMs (thread serial numbers) according to |