mmc: mediatek: refine msdc timeout api

Extract msdc timeout api common part to have
better code architecture and avoid redundant code.
Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/1595205759-5825-3-git-send-email-chun-hung.wu@mediatek.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/mtk-sd.c

@@ -723,21 +723,21 @@ static void msdc_unprepare_data(struct msdc_host *host, struct mmc_request *mrq)
 	}
 }
 
-/* clock control primitives */
-static void msdc_set_timeout(struct msdc_host *host, u32 ns, u32 clks)
+static u64 msdc_timeout_cal(struct msdc_host *host, u64 ns, u64 clks)
 {
-	u32 timeout, clk_ns;
+	u64 timeout, clk_ns;
 	u32 mode = 0;
 
-	host->timeout_ns = ns;
-	host->timeout_clks = clks;
 	if (host->mmc->actual_clock == 0) {
 		timeout = 0;
 	} else {
-		clk_ns  = 1000000000UL / host->mmc->actual_clock;
-		timeout = (ns + clk_ns - 1) / clk_ns + clks;
+		clk_ns  = 1000000000ULL;
+		do_div(clk_ns, host->mmc->actual_clock);
+		timeout = ns + clk_ns - 1;
+		do_div(timeout, clk_ns);
+		timeout += clks;
 		/* in 1048576 sclk cycle unit */
-		timeout = (timeout + (0x1 << 20) - 1) >> 20;
+		timeout = DIV_ROUND_UP(timeout, (0x1 << 20));
 		if (host->dev_comp->clk_div_bits == 8)
 			sdr_get_field(host->base + MSDC_CFG,
 				      MSDC_CFG_CKMOD, &mode);
@@ -747,9 +747,21 @@ static void msdc_set_timeout(struct msdc_host *host, u32 ns, u32 clks)
 		/*DDR mode will double the clk cycles for data timeout */
 		timeout = mode >= 2 ? timeout * 2 : timeout;
 		timeout = timeout > 1 ? timeout - 1 : 0;
-		timeout = timeout > 255 ? 255 : timeout;
 	}
-	sdr_set_field(host->base + SDC_CFG, SDC_CFG_DTOC, timeout);
+	return timeout;
+}
+
+/* clock control primitives */
+static void msdc_set_timeout(struct msdc_host *host, u64 ns, u64 clks)
+{
+	u64 timeout;
+
+	host->timeout_ns = ns;
+	host->timeout_clks = clks;
+
+	timeout = msdc_timeout_cal(host, ns, clks);
+	sdr_set_field(host->base + SDC_CFG, SDC_CFG_DTOC,
+		      (u32)(timeout > 255 ? 255 : timeout));
 }
 
 static void msdc_gate_clock(struct msdc_host *host)