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i2c: rcar: add FastMode+ support for Gen4
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To support FM+, we mainly need to turn the SMD constant into a parameter
and set it accordingly. That also means we can finally fix SMD to our
needs instead of bailing out. A sanity check for SMD then becomes a
sanity check for 'x == 0'. After all that, activating the enable bit for
FM+ is all we need to do. Tested with a Renesas Falcon board using R-Car
V3U.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
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Wolfram Sang authored and Wolfram Sang committed Jan 18, 2024
1 parent 2b523c4 commit d0520eb
Showing 1 changed file with 27 additions and 11 deletions.
38 changes: 27 additions & 11 deletions drivers/i2c/busses/i2c-rcar.c
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,7 @@
#define TMDMAE BIT(0) /* DMA Master Transmitted Enable */

/* ICCCR2 */
#define FMPE BIT(7) /* Fast Mode Plus Enable */
#define CDFD BIT(2) /* CDF Disable */
#define HLSE BIT(1) /* HIGH/LOW Separate Control Enable */
#define SME BIT(0) /* SCL Mask Enable */
Expand Down Expand Up @@ -122,11 +123,12 @@
#define ID_NACK BIT(4)
#define ID_EPROTO BIT(5)
/* persistent flags */
#define ID_P_FMPLUS BIT(27)
#define ID_P_NOT_ATOMIC BIT(28)
#define ID_P_HOST_NOTIFY BIT(29)
#define ID_P_NO_RXDMA BIT(30) /* HW forbids RXDMA sometimes */
#define ID_P_PM_BLOCKED BIT(31)
#define ID_P_MASK GENMASK(31, 28)
#define ID_P_MASK GENMASK(31, 27)

enum rcar_i2c_type {
I2C_RCAR_GEN1,
Expand All @@ -149,6 +151,7 @@ struct rcar_i2c_priv {
u32 icccr;
u16 schd;
u16 scld;
u8 smd;
u8 recovery_icmcr; /* protected by adapter lock */
enum rcar_i2c_type devtype;
struct i2c_client *slave;
Expand Down Expand Up @@ -240,9 +243,14 @@ static void rcar_i2c_init(struct rcar_i2c_priv *priv)
if (priv->devtype < I2C_RCAR_GEN3) {
rcar_i2c_write(priv, ICCCR, priv->icccr);
} else {
rcar_i2c_write(priv, ICCCR2, CDFD | HLSE | SME);
u32 icccr2 = CDFD | HLSE | SME;

if (priv->flags & ID_P_FMPLUS)
icccr2 |= FMPE;

rcar_i2c_write(priv, ICCCR2, icccr2);
rcar_i2c_write(priv, ICCCR, priv->icccr);
rcar_i2c_write(priv, ICMPR, RCAR_DEFAULT_SMD);
rcar_i2c_write(priv, ICMPR, priv->smd);
rcar_i2c_write(priv, ICHPR, priv->schd);
rcar_i2c_write(priv, ICLPR, priv->scld);
rcar_i2c_write(priv, ICFBSCR, TCYC17);
Expand Down Expand Up @@ -279,6 +287,7 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv)

/* Fall back to previously used values if not supplied */
i2c_parse_fw_timings(dev, &t, false);
priv->smd = RCAR_DEFAULT_SMD;

/*
* calculate SCL clock
Expand All @@ -304,6 +313,11 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv)
if (cdf >= 1U << cdf_width)
goto err_no_val;

if (t.bus_freq_hz > I2C_MAX_FAST_MODE_FREQ && priv->devtype >= I2C_RCAR_GEN4)
priv->flags |= ID_P_FMPLUS;
else
priv->flags &= ~ID_P_FMPLUS;

/* On Gen3+, we use cdf only for the filters, not as a SCL divider */
ick = rate / (priv->devtype < I2C_RCAR_GEN3 ? (cdf + 1) : 1);

Expand Down Expand Up @@ -345,30 +359,30 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv)
* x as a base value for the SCLD/SCHD ratio:
*
* SCL = clkp / (8 + 2 * SMD + SCLD + SCHD + F[(ticf + tr + intd) * clkp])
* SCL = clkp / (8 + 2 * RCAR_DEFAULT_SMD + RCAR_SCLD_RATIO * x
* SCL = clkp / (8 + 2 * SMD + RCAR_SCLD_RATIO * x
* + RCAR_SCHD_RATIO * x + F[...])
*
* with: sum_ratio = RCAR_SCLD_RATIO + RCAR_SCHD_RATIO
* and: smd = RCAR_DEFAULT_SMD
*
* SCL = clkp / (8 + 2 * smd + sum_ratio * x + F[...])
* 8 + 2 * smd + sum_ratio * x + F[...] = clkp / SCL
* x = ((clkp / SCL) - 8 - 2 * smd - F[...]) / sum_ratio
*/
x = DIV_ROUND_UP(rate, t.bus_freq_hz ?: 1);
x = DIV_ROUND_UP(x - 8 - 2 * RCAR_DEFAULT_SMD - round, sum_ratio);
scl = rate / (8 + 2 * RCAR_DEFAULT_SMD + sum_ratio * x + round);
x = DIV_ROUND_UP(x - 8 - 2 * priv->smd - round, sum_ratio);
scl = rate / (8 + 2 * priv->smd + sum_ratio * x + round);

/* Bail out if values don't fit into 16 bit or SMD became too large */
if (x * RCAR_SCLD_RATIO > 0xffff || RCAR_DEFAULT_SMD > x * RCAR_SCHD_RATIO)
if (x == 0 || x * RCAR_SCLD_RATIO > 0xffff)
goto err_no_val;

priv->icccr = cdf;
priv->schd = RCAR_SCHD_RATIO * x;
priv->scld = RCAR_SCLD_RATIO * x;
if (priv->smd >= priv->schd)
priv->smd = priv->schd - 1;

dev_dbg(dev, "clk %u/%u(%lu), round %u, CDF: %u SCHD %u SCLD %u\n",
scl, t.bus_freq_hz, rate, round, cdf, priv->schd, priv->scld);
dev_dbg(dev, "clk %u/%u(%lu), round %u, CDF: %u SCHD %u SCLD %u SMD %u\n",
scl, t.bus_freq_hz, rate, round, cdf, priv->schd, priv->scld, priv->smd);
}

return 0;
Expand Down Expand Up @@ -1073,6 +1087,8 @@ static const struct of_device_id rcar_i2c_dt_ids[] = {
{ .compatible = "renesas,i2c-r8a7794", .data = (void *)I2C_RCAR_GEN2 },
{ .compatible = "renesas,i2c-r8a7795", .data = (void *)I2C_RCAR_GEN3 },
{ .compatible = "renesas,i2c-r8a7796", .data = (void *)I2C_RCAR_GEN3 },
/* S4 has no FM+ bit */
{ .compatible = "renesas,i2c-r8a779f0", .data = (void *)I2C_RCAR_GEN3 },
{ .compatible = "renesas,rcar-gen1-i2c", .data = (void *)I2C_RCAR_GEN1 },
{ .compatible = "renesas,rcar-gen2-i2c", .data = (void *)I2C_RCAR_GEN2 },
{ .compatible = "renesas,rcar-gen3-i2c", .data = (void *)I2C_RCAR_GEN3 },
Expand Down

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