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Date:      Sat, 11 May 2019 15:03:51 +0000 (UTC)
From:      Emmanuel Vadot <manu@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r347491 - head/sys/dev/iicbus/twsi
Message-ID:  <201905111503.x4BF3pij096497@repo.freebsd.org>
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Author: manu
Date: Sat May 11 15:03:51 2019
New Revision: 347491
URL: https://svnweb.freebsd.org/changeset/base/347491

Log:
  twsi: Calculate the clock param based on the bus frequency
  
  Instead of precalculating the different speed, respect the bus frequency
  and calculate the clock register parameter based on it.
  If the platform didn't register the core clk, fallback on the precomputed
  values (This is likely do be the case on Marvell boards).

Modified:
  head/sys/dev/iicbus/twsi/a10_twsi.c
  head/sys/dev/iicbus/twsi/twsi.c

Modified: head/sys/dev/iicbus/twsi/a10_twsi.c
==============================================================================
--- head/sys/dev/iicbus/twsi/a10_twsi.c	Sat May 11 15:02:55 2019	(r347490)
+++ head/sys/dev/iicbus/twsi/a10_twsi.c	Sat May 11 15:03:51 2019	(r347491)
@@ -87,9 +87,7 @@ static int
 a10_twsi_attach(device_t dev)
 {
 	struct twsi_softc *sc;
-	clk_t clk;
 	hwreset_t rst;
-	uint64_t freq;
 	int error;
 
 	sc = device_get_softc(dev);
@@ -104,12 +102,12 @@ a10_twsi_attach(device_t dev)
 	}
 
 	/* Activate clock */
-	error = clk_get_by_ofw_index(dev, 0, 0, &clk);
+	error = clk_get_by_ofw_index(dev, 0, 0, &sc->clk_core);
 	if (error != 0) {
 		device_printf(dev, "could not find clock\n");
 		return (error);
 	}
-	error = clk_enable(clk);
+	error = clk_enable(sc->clk_core);
 	if (error != 0) {
 		device_printf(dev, "could not enable clock\n");
 		return (error);
@@ -122,31 +120,6 @@ a10_twsi_attach(device_t dev)
 	sc->reg_status = TWI_STAT;
 	sc->reg_baud_rate = TWI_CCR;
 	sc->reg_soft_reset = TWI_SRST;
-
-	/* Setup baud rate params */
-	clk_get_freq(clk, &freq);
-	switch (freq) {
-		/* 
-		 * Formula is
-		 * F0 = FINT / 2 ^ CLK_N
-		 * F1 = F0 / (CLK_M + 1)
-		 * 
-		 * Doc says that the output freq is F1/10 but my logic analyzer says otherwise
-		 */
-	case 48000000:
-		sc->baud_rate[IIC_SLOW].param = TWSI_BAUD_RATE_PARAM(11, 1);
-		sc->baud_rate[IIC_FAST].param = TWSI_BAUD_RATE_PARAM(11, 1);
-		sc->baud_rate[IIC_FASTEST].param = TWSI_BAUD_RATE_PARAM(2, 1);
-		break;
-	case 24000000:
-		sc->baud_rate[IIC_SLOW].param = TWSI_BAUD_RATE_PARAM(5, 2);
-		sc->baud_rate[IIC_FAST].param = TWSI_BAUD_RATE_PARAM(5, 2);
-		sc->baud_rate[IIC_FASTEST].param = TWSI_BAUD_RATE_PARAM(2, 2);
-		break;
-	default:
-		device_printf(dev, "Non supported frequency\n");
-		return (ENXIO);
-	}
 
 	sc->need_ack = true;
 	return (twsi_attach(dev));

Modified: head/sys/dev/iicbus/twsi/twsi.c
==============================================================================
--- head/sys/dev/iicbus/twsi/twsi.c	Sat May 11 15:02:55 2019	(r347490)
+++ head/sys/dev/iicbus/twsi/twsi.c	Sat May 11 15:03:51 2019	(r347491)
@@ -243,6 +243,43 @@ twsi_locked_start(device_t dev, struct twsi_softc *sc,
 	return (IIC_NOERR);
 }
 
+#ifdef EXT_RESOURCES
+#define	TWSI_BAUD_RATE_RAW(C,M,N)	((C)/((10*(M+1))<<(N)))
+#define	ABSSUB(a,b)	(((a) > (b)) ? (a) - (b) : (b) - (a))
+
+static int
+twsi_calc_baud_rate(struct twsi_softc *sc, const u_int target,
+  int *param)
+{
+	uint64_t clk;
+	uint32_t cur, diff, diff0;
+	int m, n, m0, n0;
+
+	/* Calculate baud rate. */
+	diff0 = 0xffffffff;
+
+	if (clk_get_freq(sc->clk_core, &clk) < 0)
+		return (-1);
+
+	debugf(sc->dev, "Bus clock is at %lu\n", clk);
+
+	for (n = 0; n < 8; n++) {
+		for (m = 0; m < 16; m++) {
+			cur = TWSI_BAUD_RATE_RAW(clk,m,n);
+			diff = ABSSUB(target, cur);
+			if (diff < diff0) {
+				m0 = m;
+				n0 = n;
+				diff0 = diff;
+			}
+		}
+	}
+	*param = TWSI_BAUD_RATE_PARAM(m0, n0);
+
+	return (0);
+}
+#endif /* EXT_RESOURCES */
+
 /*
  * Only slave mode supported, disregard [old]addr
  */
@@ -251,24 +288,36 @@ twsi_reset(device_t dev, u_char speed, u_char addr, u_
 {
 	struct twsi_softc *sc;
 	uint32_t param;
-	/* uint32_t val; */
+#ifdef EXT_RESOURCES
+	u_int busfreq;
+#endif
 
 	sc = device_get_softc(dev);
 
-	switch (speed) {
-	case IIC_SLOW:
-	case IIC_FAST:
-		param = sc->baud_rate[speed].param;
-		debugf(dev, "Using IIC_FAST mode with speed param=%x\n", param);
-		break;
-	case IIC_FASTEST:
-	case IIC_UNKNOWN:
-	default:
-		param = sc->baud_rate[IIC_FAST].param;
-		debugf(dev, "Using IIC_FASTEST/UNKNOWN mode with speed param=%x\n", param);
-		break;
+#ifdef EXT_RESOURCES
+	busfreq = IICBUS_GET_FREQUENCY(sc->iicbus, speed);
+
+	if (twsi_calc_baud_rate(sc, busfreq, &param) == -1) {
+#endif
+		switch (speed) {
+		case IIC_SLOW:
+		case IIC_FAST:
+			param = sc->baud_rate[speed].param;
+			debugf(dev, "Using IIC_FAST mode with speed param=%x\n", param);
+			break;
+		case IIC_FASTEST:
+		case IIC_UNKNOWN:
+		default:
+			param = sc->baud_rate[IIC_FAST].param;
+			debugf(dev, "Using IIC_FASTEST/UNKNOWN mode with speed param=%x\n", param);
+			break;
+		}
+#ifdef EXT_RESOURCES
 	}
+#endif
 
+	debugf(dev, "Using clock param=%x\n", param);
+
 	mtx_lock(&sc->mutex);
 	TWSI_WRITE(sc, sc->reg_soft_reset, 0x0);
 	TWSI_WRITE(sc, sc->reg_baud_rate, param);
@@ -521,6 +570,7 @@ twsi_intr(void *arg)
 			break;
 
 		case TWSI_STATUS_ADDR_R_ACK:
+			debugf(sc->dev, "Ack received after transmitting the address\n");
 			sc->recv_bytes = 0;
 
 			TWSI_WRITE(sc, sc->reg_control, sc->control_val);

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