blob: 23717d8dc9e86968854b65e3ad088f548d51522f [file] [log] [blame]
From b1201193f43dbbc8d5ebdf82fd37a4c8954b95b0 Mon Sep 17 00:00:00 2001
From: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Date: Fri, 13 Apr 2018 15:44:17 +0300
Subject: [PATCH 1241/1795] spi: sh-msiof: Simplify calculation of divisors for
transfer rate
The change updates sh_msiof_spi_set_clk_regs() function by iterating
over BRDV power values. Note that the change is a functional one, namely
prescaler output x 1/1 set in BRDV bit field (0b111) for MSO division
rate set to 2 is substituted by BRDV = 0b000 and BRPS = 0b0, in terms
of written values to TSCR setting of 0x0107 is substituted by 0x0000,
and for all input parameter cases this is the only functional change,
which touches the controller.
As a result of the rework the function is supposed to be slightly more
efficient and more readable and maintainable in case of any further
extensions.
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
(cherry picked from commit 51093cba290a375d51749d5bd61835809fa44853)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
drivers/spi/spi-sh-msiof.c | 67 ++++++++++++++++++++------------------
1 file changed, 35 insertions(+), 32 deletions(-)
diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index c1ea7965fe27..d1c51b49c8ce 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -38,7 +38,7 @@ struct sh_msiof_chipdata {
u16 tx_fifo_size;
u16 rx_fifo_size;
u16 master_flags;
- u16 min_div;
+ u16 min_div_pow;
};
struct sh_msiof_spi_priv {
@@ -50,7 +50,7 @@ struct sh_msiof_spi_priv {
struct completion done;
unsigned int tx_fifo_size;
unsigned int rx_fifo_size;
- unsigned int min_div;
+ unsigned int min_div_pow;
void *tx_dma_page;
void *rx_dma_page;
dma_addr_t tx_dma_addr;
@@ -243,43 +243,46 @@ static irqreturn_t sh_msiof_spi_irq(int irq, void *data)
return IRQ_HANDLED;
}
-static struct {
- unsigned short div;
- 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 const u32 sh_msiof_spi_div_array[] = {
+ SCR_BRDV_DIV_1, SCR_BRDV_DIV_2, SCR_BRDV_DIV_4,
+ SCR_BRDV_DIV_8, SCR_BRDV_DIV_16, 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;
+ unsigned long div;
u32 brps, scr;
- size_t k;
+ unsigned int div_pow = p->min_div_pow;
- if (!WARN_ON(!spi_hz || !parent_rate))
- div = DIV_ROUND_UP(parent_rate, spi_hz);
-
- div = max_t(unsigned long, div, p->min_div);
+ if (!spi_hz || !parent_rate) {
+ WARN(1, "Invalid clock rate parameters %lu and %u\n",
+ parent_rate, spi_hz);
+ return;
+ }
- for (k = 0; k < ARRAY_SIZE(sh_msiof_spi_div_table); k++) {
- brps = DIV_ROUND_UP(div, sh_msiof_spi_div_table[k].div);
+ div = DIV_ROUND_UP(parent_rate, spi_hz);
+ if (div <= 1024) {
/* SCR_BRDV_DIV_1 is valid only if BRPS is x 1/1 or x 1/2 */
- if (sh_msiof_spi_div_table[k].div == 1 && brps > 2)
- continue;
- if (brps <= 32) /* max of brdv is 32 */
- break;
- }
+ if (!div_pow && div <= 32 && div > 2)
+ div_pow = 1;
- k = min_t(int, k, ARRAY_SIZE(sh_msiof_spi_div_table) - 1);
- brps = min_t(int, brps, 32);
+ if (div_pow)
+ brps = (div + 1) >> div_pow;
+ else
+ brps = div;
+
+ for (; brps > 32; div_pow++)
+ brps = (brps + 1) >> 1;
+ } else {
+ /* Set transfer rate composite divisor to 2^5 * 32 = 1024 */
+ dev_err(&p->pdev->dev,
+ "Requested SPI transfer rate %d is too low\n", spi_hz);
+ div_pow = 5;
+ brps = 32;
+ }
- scr = sh_msiof_spi_div_table[k].brdv | SCR_BRPS(brps);
+ scr = sh_msiof_spi_div_array[div_pow] | SCR_BRPS(brps);
sh_msiof_write(p, TSCR, scr);
if (!(p->master->flags & SPI_MASTER_MUST_TX))
sh_msiof_write(p, RSCR, scr);
@@ -1028,21 +1031,21 @@ static const struct sh_msiof_chipdata sh_data = {
.tx_fifo_size = 64,
.rx_fifo_size = 64,
.master_flags = 0,
- .min_div = 1,
+ .min_div_pow = 0,
};
static const struct sh_msiof_chipdata rcar_gen2_data = {
.tx_fifo_size = 64,
.rx_fifo_size = 64,
.master_flags = SPI_MASTER_MUST_TX,
- .min_div = 1,
+ .min_div_pow = 0,
};
static const struct sh_msiof_chipdata rcar_gen3_data = {
.tx_fifo_size = 64,
.rx_fifo_size = 64,
.master_flags = SPI_MASTER_MUST_TX,
- .min_div = 2,
+ .min_div_pow = 1,
};
static const struct of_device_id sh_msiof_match[] = {
@@ -1267,7 +1270,7 @@ static int sh_msiof_spi_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, p);
p->master = master;
p->info = info;
- p->min_div = chipdata->min_div;
+ p->min_div_pow = chipdata->min_div_pow;
init_completion(&p->done);
--
2.19.0