mmc: sdhci-of-at91: avoid division by zero

Avoid division by zero and setting invalid values to address pointed
by SDHCI_PRESET_FOR_SDR104.

Fixes: bac9f2f ("mmc: sdhci-of-at91: add preset for HS400 mode")
Fixes: d85a069 ("mmc: sdhci-of-at91: add compatible to sama7g5 SoC")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Eugen Hristev <eugen.hristev@microchip.com>

Author: claudiubeznea

drivers/mmc/host/sdhci-of-at91.c

@@ -306,15 +306,21 @@ static int sdhci_at91_set_clks_presets(struct device *dev)
 	preset_div = DIV_ROUND_UP(gck_rate, 100000000) - 1;
 	writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
 	       host->ioaddr + SDHCI_PRESET_FOR_SDR50);
-	preset_div = DIV_ROUND_UP(gck_rate, priv->soc_data->max_sdr104_clk) - 1;
-	writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
-	       host->ioaddr + SDHCI_PRESET_FOR_SDR104);
+	if (priv->soc_data->max_sdr104_clk) {
+		preset_div = DIV_ROUND_UP(gck_rate,
+					  priv->soc_data->max_sdr104_clk) - 1;
+		writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
+		       host->ioaddr + SDHCI_PRESET_FOR_SDR104);
+	}
 	preset_div = DIV_ROUND_UP(gck_rate, 50000000) - 1;
 	writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
 	       host->ioaddr + SDHCI_PRESET_FOR_DDR50);
-	preset_div = DIV_ROUND_UP(gck_rate, priv->soc_data->max_sdr104_clk) - 1;
-	writew(SDHCI_AT91_PRESET_DRVA_CONF | preset_div,
-	       host->ioaddr + SDHCI_PRESET_FOR_HS400);
+	if (priv->soc_data->max_sdr104_clk) {
+		preset_div = DIV_ROUND_UP(gck_rate,
+					  priv->soc_data->max_sdr104_clk) - 1;
+		writew(SDHCI_AT91_PRESET_DRVA_CONF | preset_div,
+		       host->ioaddr + SDHCI_PRESET_FOR_HS400);
+	}
 
 	clk_prepare_enable(priv->mainck);
 	clk_prepare_enable(priv->gck);