[PATCH 3/3] i2c: rcar: add FastMode+ support
From: Wolfram Sang
Date: Mon Sep 04 2023 - 09:59:13 EST
Apply the different formula and register setting for activating FM+ on
Gen4 devtypes.
Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-rcar.c | 125 ++++++++++++++++++++++++----------
1 file changed, 89 insertions(+), 36 deletions(-)
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 76aa16bf17b2..a48849b393a3 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -41,6 +41,10 @@
#define ICSAR 0x1C /* slave address */
#define ICMAR 0x20 /* master address */
#define ICRXTX 0x24 /* data port */
+#define ICCCR2 0x28 /* Clock control 2 */
+#define ICMPR 0x2C /* SCL mask control */
+#define ICHPR 0x30 /* SCL HIGH control */
+#define ICLPR 0x34 /* SCL LOW control */
#define ICFBSCR 0x38 /* first bit setup cycle (Gen3) */
#define ICDMAER 0x3c /* DMA enable (Gen3) */
@@ -84,6 +88,12 @@
#define RMDMAE BIT(1) /* DMA Master Received Enable */
#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 */
+
/* ICFBSCR */
#define TCYC17 0x0f /* 17*Tcyc delay 1st bit between SDA and SCL */
@@ -104,11 +114,12 @@
#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,
@@ -128,7 +139,7 @@ struct rcar_i2c_priv {
wait_queue_head_t wait;
int pos;
- u32 icccr;
+ u32 clock_val;
u8 recovery_icmcr; /* protected by adapter lock */
enum rcar_i2c_type devtype;
struct i2c_client *slave;
@@ -217,7 +228,17 @@ static void rcar_i2c_init(struct rcar_i2c_priv *priv)
rcar_i2c_write(priv, ICMCR, MDBS);
rcar_i2c_write(priv, ICMSR, 0);
/* start clock */
- rcar_i2c_write(priv, ICCCR, priv->icccr);
+ if (priv->flags & ID_P_FMPLUS) {
+ rcar_i2c_write(priv, ICCCR, 0);
+ rcar_i2c_write(priv, ICMPR, priv->clock_val);
+ rcar_i2c_write(priv, ICHPR, 3 * priv->clock_val);
+ rcar_i2c_write(priv, ICLPR, 3 * priv->clock_val);
+ rcar_i2c_write(priv, ICCCR2, FMPE | CDFD | HLSE | SME);
+ } else {
+ rcar_i2c_write(priv, ICCCR, priv->clock_val);
+ if (priv->devtype >= I2C_RCAR_GEN3)
+ rcar_i2c_write(priv, ICCCR2, 0);
+ }
if (priv->devtype >= I2C_RCAR_GEN3)
rcar_i2c_write(priv, ICFBSCR, TCYC17);
@@ -242,7 +263,7 @@ static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv)
static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv)
{
- u32 scgd, cdf, round, ick, sum, scl, cdf_width;
+ u32 scgd, cdf = 0, round, ick, sum, scl, cdf_width, smd;
unsigned long rate;
struct device *dev = rcar_i2c_priv_to_dev(priv);
struct i2c_timings t = {
@@ -252,19 +273,26 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv)
.scl_int_delay_ns = 50,
};
- cdf_width = (priv->devtype == I2C_RCAR_GEN1) ? 2 : 3;
-
/* Fall back to previously used values if not supplied */
i2c_parse_fw_timings(dev, &t, false);
+ 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;
+
/*
* calculate SCL clock
* see
- * ICCCR
+ * ICCCR (and ICCCR2 for FastMode+)
*
* ick = clkp / (1 + CDF)
* SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
*
+ * for FastMode+:
+ * SCL = clkp / (8 + SMD * 2 + SCLD + SCHD +F[(ticf + tr + intd) * clkp])
+ *
* ick : I2C internal clock < 20 MHz
* ticf : I2C SCL falling time
* tr : I2C SCL rising time
@@ -273,10 +301,14 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv)
* F[] : integer up-valuation
*/
rate = clk_get_rate(priv->clk);
- cdf = rate / 20000000;
- if (cdf >= 1U << cdf_width) {
- dev_err(dev, "Input clock %lu too high\n", rate);
- return -EIO;
+
+ if (!(priv->flags & ID_P_FMPLUS)) {
+ cdf = rate / 20000000;
+ cdf_width = (priv->devtype == I2C_RCAR_GEN1) ? 2 : 3;
+ if (cdf >= 1U << cdf_width) {
+ dev_err(dev, "Input clock %lu too high\n", rate);
+ return -EIO;
+ }
}
ick = rate / (cdf + 1);
@@ -292,34 +324,55 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv)
round = (ick + 500000) / 1000000 * sum;
round = (round + 500) / 1000;
- /*
- * SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
- *
- * Calculation result (= SCL) should be less than
- * bus_speed for hardware safety
- *
- * We could use something along the lines of
- * div = ick / (bus_speed + 1) + 1;
- * scgd = (div - 20 - round + 7) / 8;
- * scl = ick / (20 + (scgd * 8) + round);
- * (not fully verified) but that would get pretty involved
- */
- for (scgd = 0; scgd < 0x40; scgd++) {
- scl = ick / (20 + (scgd * 8) + round);
- if (scl <= t.bus_freq_hz)
- break;
- }
+ if (priv->flags & ID_P_FMPLUS) {
+ /*
+ * SMD should be smaller than SCLD and SCHD, we arbitrarily set
+ * the ratio 1:3. SCHD:SCLD ratio is 1:1, thus:
+ * SCL = clkp / (8 + SMD * 2 + SCLD + SCHD + F[(ticf + tr + intd) * clkp])
+ * SCL = clkp / (8 + SMD * 2 + SMD * 3 + SMD * 3 + F[...])
+ * SCL = clkp / (8 + SMD * 8 + F[...])
+ */
+ smd = DIV_ROUND_UP(ick / t.bus_freq_hz - 8 - round, 8);
+ scl = ick / (8 + 8 * smd + round);
- if (scgd == 0x40) {
- dev_err(dev, "it is impossible to calculate best SCL\n");
- return -EIO;
- }
+ if (smd > 0xff) {
+ dev_err(dev, "it is impossible to calculate best SCL\n");
+ return -EINVAL;
+ }
- dev_dbg(dev, "clk %d/%d(%lu), round %u, CDF:0x%x, SCGD: 0x%x\n",
- scl, t.bus_freq_hz, rate, round, cdf, scgd);
+ dev_dbg(dev, "clk %d/%d(%lu), round %u, SMD:0x%x, SCHD: 0x%x\n",
+ scl, t.bus_freq_hz, rate, round, smd, 3 * smd);
- /* keep icccr value */
- priv->icccr = scgd << cdf_width | cdf;
+ priv->clock_val = smd;
+ } else {
+ /*
+ * SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
+ *
+ * Calculation result (= SCL) should be less than
+ * bus_speed for hardware safety
+ *
+ * We could use something along the lines of
+ * div = ick / (bus_speed + 1) + 1;
+ * scgd = (div - 20 - round + 7) / 8;
+ * scl = ick / (20 + (scgd * 8) + round);
+ * (not fully verified) but that would get pretty involved
+ */
+ for (scgd = 0; scgd < 0x40; scgd++) {
+ scl = ick / (20 + (scgd * 8) + round);
+ if (scl <= t.bus_freq_hz)
+ break;
+ }
+
+ if (scgd == 0x40) {
+ dev_err(dev, "it is impossible to calculate best SCL\n");
+ return -EINVAL;
+ }
+
+ dev_dbg(dev, "clk %d/%d(%lu), round %u, CDF:0x%x, SCGD: 0x%x\n",
+ scl, t.bus_freq_hz, rate, round, cdf, scgd);
+
+ priv->clock_val = scgd << cdf_width | cdf;
+ }
return 0;
}
--
2.35.1