i2c: rcar: add FastMode+ support for Gen4

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>

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 973811a6c27ba36b8f44d4958d169f0384b30ae6..828aa2ea0fe4c90785cbdc5e65b5b28cdf86b40b 100644 (file)
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -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 */
@@ -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,
@@ -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;
@@ -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);
@@ -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
@@ -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);
 
@@ -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;
@@ -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 },