+static u32 radeon_get_i2c_prescale(struct radeon_device *rdev)
+{
+ struct radeon_pll *spll = &rdev->clock.spll;
+ u32 sclk = radeon_get_engine_clock(rdev);
+ u32 prescale = 0;
+ u32 n, m;
+ u8 loop;
+ int i2c_clock;
+
+ switch (rdev->family) {
+ case CHIP_R100:
+ case CHIP_RV100:
+ case CHIP_RS100:
+ case CHIP_RV200:
+ case CHIP_RS200:
+ case CHIP_R200:
+ case CHIP_RV250:
+ case CHIP_RS300:
+ case CHIP_RV280:
+ case CHIP_R300:
+ case CHIP_R350:
+ case CHIP_RV350:
+ n = (spll->reference_freq) / (4 * 6);
+ for (loop = 1; loop < 255; loop++) {
+ if ((loop * (loop - 1)) > n)
+ break;
+ }
+ m = loop - 1;
+ prescale = m | (loop << 8);
+ break;
+ case CHIP_RV380:
+ case CHIP_RS400:
+ case CHIP_RS480:
+ case CHIP_R420:
+ case CHIP_R423:
+ case CHIP_RV410:
+ sclk = radeon_get_engine_clock(rdev);
+ prescale = (((sclk * 10)/(4 * 128 * 100) + 1) << 8) + 128;
+ break;
+ case CHIP_RS600:
+ case CHIP_RS690:
+ case CHIP_RS740:
+ /* todo */
+ break;
+ case CHIP_RV515:
+ case CHIP_R520:
+ case CHIP_RV530:
+ case CHIP_RV560:
+ case CHIP_RV570:
+ case CHIP_R580:
+ i2c_clock = 50;
+ sclk = radeon_get_engine_clock(rdev);
+ if (rdev->family == CHIP_R520)
+ prescale = (127 << 8) + ((sclk * 10) / (4 * 127 * i2c_clock));
+ else
+ prescale = (((sclk * 10)/(4 * 128 * 100) + 1) << 8) + 128;
+ break;
+ case CHIP_R600:
+ case CHIP_RV610:
+ case CHIP_RV630:
+ case CHIP_RV670:
+ /* todo */
+ break;
+ case CHIP_RV620:
+ case CHIP_RV635:
+ case CHIP_RS780:
+ case CHIP_RS880:
+ case CHIP_RV770:
+ case CHIP_RV730:
+ case CHIP_RV710:
+ case CHIP_RV740:
+ /* todo */
+ break;
+ default:
+ DRM_ERROR("i2c: unhandled radeon chip\n");
+ break;
+ }
+ return prescale;
+}
+
+