spi: sh-msiof: Update calculation of frequency dividing

sh-msiof of frequency dividing does not perform the calculation, driver have
to manage setting value in the table. It is not possible to set frequency
dividing value close to the actual data in this way. This changes from
frequency dividing of table management to setting by calculation.
This driver is able to set a value close to the actual data.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-sh-msiof.c

@@ -243,42 +243,38 @@ static irqreturn_t sh_msiof_spi_irq(int irq, void *data)
 
 static struct {
 	unsigned short div;
-	unsigned short scr;
-} const sh_msiof_spi_clk_table[] = {
-	{ 1,	SCR_BRPS( 1) | SCR_BRDV_DIV_1 },
-	{ 2,	SCR_BRPS( 1) | SCR_BRDV_DIV_2 },
-	{ 4,	SCR_BRPS( 1) | SCR_BRDV_DIV_4 },
-	{ 8,	SCR_BRPS( 1) | SCR_BRDV_DIV_8 },
-	{ 16,	SCR_BRPS( 1) | SCR_BRDV_DIV_16 },
-	{ 32,	SCR_BRPS( 1) | SCR_BRDV_DIV_32 },
-	{ 64,	SCR_BRPS(32) | SCR_BRDV_DIV_2 },
-	{ 128,	SCR_BRPS(32) | SCR_BRDV_DIV_4 },
-	{ 256,	SCR_BRPS(32) | SCR_BRDV_DIV_8 },
-	{ 512,	SCR_BRPS(32) | SCR_BRDV_DIV_16 },
-	{ 1024,	SCR_BRPS(32) | SCR_BRDV_DIV_32 },
+	unsigned short brdv;
+} const sh_msiof_spi_div_table[] = {
+	{ 1,	SCR_BRDV_DIV_1 },
+	{ 2,	SCR_BRDV_DIV_2 },
+	{ 4,	SCR_BRDV_DIV_4 },
+	{ 8,	SCR_BRDV_DIV_8 },
+	{ 16,	SCR_BRDV_DIV_16 },
+	{ 32,	SCR_BRDV_DIV_32 },
 };
 
 static void sh_msiof_spi_set_clk_regs(struct sh_msiof_spi_priv *p,
 				      unsigned long parent_rate, u32 spi_hz)
 {
 	unsigned long div = 1024;
+	u32 brps, scr;
 	size_t k;
 
 	if (!WARN_ON(!spi_hz || !parent_rate))
 		div = DIV_ROUND_UP(parent_rate, spi_hz);
 
-	/* TODO: make more fine grained */
-
-	for (k = 0; k < ARRAY_SIZE(sh_msiof_spi_clk_table); k++) {
-		if (sh_msiof_spi_clk_table[k].div >= div)
+	for (k = 0; k < ARRAY_SIZE(sh_msiof_spi_div_table); k++) {
+		brps = DIV_ROUND_UP(div, sh_msiof_spi_div_table[k].div);
+		if (brps <= 32) /* max of brdv is 32 */
 			break;
 	}
 
-	k = min_t(int, k, ARRAY_SIZE(sh_msiof_spi_clk_table) - 1);
+	k = min_t(int, k, ARRAY_SIZE(sh_msiof_spi_div_table) - 1);
 
-	sh_msiof_write(p, TSCR, sh_msiof_spi_clk_table[k].scr);
+	scr = sh_msiof_spi_div_table[k].brdv | SCR_BRPS(brps);
+	sh_msiof_write(p, TSCR, scr);
 	if (!(p->chipdata->master_flags & SPI_MASTER_MUST_TX))
-		sh_msiof_write(p, RSCR, sh_msiof_spi_clk_table[k].scr);
+		sh_msiof_write(p, RSCR, scr);
 }
 
 static u32 sh_msiof_get_delay_bit(u32 dtdl_or_syncdl)