[PATCH v3 02/13] OMAP: DMA: Introduce errata handling feature

[manjugk@ti.com (G, Manjunath Kondaiah)]

Implement errata handling to use flags instead of cpu_is_*
and cpu_class_* in the code.

The errata flags are initialized at init time and during runtime
we are using the errata variable (via the IS_DMA_ERRATA macro)
to execute the required errata workaround.

Reused errata handling patch from Peter Ujfalusi <peter.ujfalusi@nokia.com>
https://patchwork.kernel.org/patch/231191/

Signed-off-by: G, Manjunath Kondaiah <manjugk@ti.com>
Cc: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
---
 arch/arm/plat-omap/dma.c              |  134 ++++++++++++++++++++++----------
 arch/arm/plat-omap/include/plat/dma.h |   11 +++
 2 files changed, 103 insertions(+), 42 deletions(-)

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index 77241e2..0ff82d0 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -195,6 +195,7 @@ enum { DMA_CHAIN_STARTED, DMA_CHAIN_NOTSTARTED };
 #define OMAP_FUNC_MUX_ARM_BASE		(0xfffe1000 + 0xec)
 
 static int enable_1510_mode;
+static u32 errata;
 
 static struct omap_dma_global_context_registers {
 	u32 dma_irqenable_l0;
@@ -1216,12 +1217,8 @@ void omap_start_dma(int lch)
 
 			cur_lch = next_lch;
 		} while (next_lch != -1);
-	} else if (cpu_is_omap242x() ||
-		(cpu_is_omap243x() &&  omap_type() <= OMAP2430_REV_ES1_0)) {
-
-		/* Errata: Need to write lch even if not using chaining */
+	} else if (IS_DMA_ERRATA(DMA_ERRATA_PARALLEL_CHANNELS))
 		dma_write(lch, CLNK_CTRL2, lch);
-	}
 
 	omap_enable_channel_irq(lch);
 
@@ -1231,17 +1228,8 @@ void omap_start_dma(int lch)
 		dma_write(l, CCR1, lch);
 	} else {
 		l = dma_read(CCR2, lch);
-		/*
-		 * Errata: Inter Frame DMA buffering issue (All OMAP2420 and
-		 * OMAP2430ES1.0): DMA will wrongly buffer elements if packing
-		 * and bursting is enabled. This might result in data gets
-		 * stalled in FIFO@the end of the block.
-		 * Workaround: DMA channels must have BUFFERING_DISABLED bit
-		 * set to guarantee no data will stay in the DMA FIFO in case
-		 * inter frame buffering occurs.
-		 */
-		if (cpu_is_omap2420() || (cpu_is_omap2430() &&
-				(omap_type() == OMAP2430_REV_ES1_0)))
+
+		if (IS_DMA_ERRATA(DMA_ERRATA_IFRAME_BUFFERING))
 			l |= OMAP_DMA_CCR_BUFFERING_DISABLE;
 
 		l |= OMAP_DMA_CCR_EN;
@@ -1253,14 +1241,14 @@ EXPORT_SYMBOL(omap_start_dma);
 
 void omap_stop_dma(int lch)
 {
-	u32 l;
+	u32 l = 0;
 
 	/* Disable all interrupts on the channel */
 	if (cpu_class_is_omap1())
 		dma_write(0, CICR1, lch);
 
-	/* OMAP3 Errata i541: sDMA FIFO draining does not finish */
-	if (cpu_is_omap34xx() && (l & OMAP_DMA_CCR_SEL_SRC_DST_SYNC)) {
+	if (IS_DMA_ERRATA(DMA_ERRATA_i541) &&
+			(l & OMAP_DMA_CCR_SEL_SRC_DST_SYNC)) {
 		int i = 0;
 		u32 sys_cf;
 
@@ -1367,11 +1355,7 @@ dma_addr_t omap_get_dma_src_pos(int lch)
 	else
 		offset = dma_read(CSAC2, lch);
 
-	/*
-	 * omap 3.2/3.3 erratum: sometimes 0 is returned if CSAC/CDAC is
-	 * read before the DMA controller finished disabling the channel.
-	 */
-	if (!cpu_is_omap15xx() && offset == 0) {
+	if (IS_DMA_ERRATA(DMA_ERRATA_3_3) && offset == 0) {
 		if (cpu_class_is_omap1())
 			offset = dma_read(CSAC1, lch);
 		else
@@ -1966,7 +1950,7 @@ int omap_stop_dma_chain_transfers(int chain_id)
 {
 	int *channels;
 	u32 l, i;
-	u32 sys_cf;
+	u32 sys_cf = 0;
 
 	/* Check for input params */
 	if (unlikely((chain_id < 0 || chain_id >= dma_lch_count))) {
@@ -1981,15 +1965,13 @@ int omap_stop_dma_chain_transfers(int chain_id)
 	}
 	channels = dma_linked_lch[chain_id].linked_dmach_q;
 
-	/*
-	 * DMA Errata:
-	 * Special programming model needed to disable DMA before end of block
-	 */
-	sys_cf = dma_read(OCP_SYSCONFIG, 0);
-	l = sys_cf;
-	/* Middle mode reg set no Standby */
-	l &= ~((1 << 12)|(1 << 13));
-	dma_write(l, OCP_SYSCONFIG, 0);
+	if (IS_DMA_ERRATA(DMA_ERRATA_i88)) {
+		sys_cf = dma_read(OCP_SYSCONFIG, 0);
+		l = sys_cf;
+		/* Middle mode reg set no Standby */
+		l &= ~((1 << 12)|(1 << 13));
+		dma_write(l, OCP_SYSCONFIG, 0);
+	}
 
 	for (i = 0; i < dma_linked_lch[chain_id].no_of_lchs_linked; i++) {
 
@@ -2008,8 +1990,8 @@ int omap_stop_dma_chain_transfers(int chain_id)
 	/* Reset the Queue pointers */
 	OMAP_DMA_CHAIN_QINIT(chain_id);
 
-	/* Errata - put in the old value */
-	dma_write(sys_cf, OCP_SYSCONFIG, 0);
+	if (IS_DMA_ERRATA(DMA_ERRATA_i88))
+		dma_write(sys_cf, OCP_SYSCONFIG, 0);
 
 	return 0;
 }
@@ -2215,12 +2197,7 @@ static int omap2_dma_handle_ch(int ch)
 	if (unlikely(status & OMAP2_DMA_TRANS_ERR_IRQ)) {
 		printk(KERN_INFO "DMA transaction error with device %d\n",
 		       dma_chan[ch].dev_id);
-		if (cpu_class_is_omap2()) {
-			/*
-			 * Errata: sDMA Channel is not disabled
-			 * after a transaction error. So we explicitely
-			 * disable the channel
-			 */
+		if (IS_DMA_ERRATA(DMA_ERRATA_i378)) {
 			u32 ccr;
 
 			ccr = dma_read(CCR2, ch);
@@ -2332,6 +2309,76 @@ void omap_dma_global_context_restore(void)
 			omap_clear_dma(ch);
 }
 
+static void configure_dma_errata(void)
+{
+
+	/*
+	 * Erratas applicable for OMAP2430ES1.0 and all omap2420
+	 *
+	 * I.
+	 * Errata ID: XX Inter Frame DMA buffering issue DMA will wrongly
+	 * buffer elements if packing and bursting is enabled. This might
+	 * result in data gets stalled in FIFO@the end of the block.
+	 * Workaround: DMA channels must have BUFFERING_DISABLED bit set to
+	 * guarantee no data will stay in the DMA FIFO in case inter frame
+	 * buffering occurs
+	 *
+	 * II.
+	 * Errata ID: XX DMA may hang when several channels are used in parallel
+	 * In the following configuration, DMA channel hanging can occur:
+	 * a. Channel i, hardware synchronized, is enabled
+	 * b. Another channel (Channel x), software synchronized, is enabled.
+	 * c. Channel i is disabled before end of transfer
+	 * d. Channel i is reenabled.
+	 * e. Steps 1 to 4 are repeated a certain number of times.
+	 * f. A third channel (Channel y), software synchronized, is enabled.
+	 * Channel x and Channel y may hang immediately after step 'f'.
+	 * Workaround:
+	 * For any channel used - make sure NextLCH_ID is set to the value j.
+	 */
+	if (cpu_is_omap2420() || (cpu_is_omap2430() &&
+				(omap_type() == OMAP2430_REV_ES1_0))) {
+
+		SET_DMA_ERRATA(DMA_ERRATA_IFRAME_BUFFERING);
+		SET_DMA_ERRATA(DMA_ERRATA_PARALLEL_CHANNELS);
+	}
+
+	/*
+	 * Errata ID: i378: OMAP2plus: sDMA Channel is not disabled
+	 * after a transaction error.
+	 * Workaround: SW should explicitely disable the channel.
+	 */
+	if (cpu_class_is_omap2())
+		SET_DMA_ERRATA(DMA_ERRATA_i378);
+
+	/*
+	 * Errata ID: i541: sDMA FIFO draining does not finish
+	 * If sDMA channel is disabled on the fly, sDMA enters standby even
+	 * through FIFO Drain is still in progress
+	 * Workaround: Put sDMA in NoStandby more before a logical channel is
+	 * disabled, then put it back to SmartStandby right after the channel
+	 * finishes FIFO draining.
+	 */
+	if (cpu_is_omap34xx())
+		SET_DMA_ERRATA(DMA_ERRATA_i541);
+
+	/*
+	 * Errata ID: i88 : Special programming model needed to disable DMA
+	 * before end of block.
+	 * Workaround: software must ensure that the DMA is configured in No
+	 * Standby mode(DMAx_OCP_SYSCONFIG.MIDLEMODE = "01")
+	 */
+	if (omap_type() == OMAP3430_REV_ES1_0)
+		SET_DMA_ERRATA(DMA_ERRATA_i88);
+
+	/*
+	 * Errata 3.2/3.3: sometimes 0 is returned if CSAC/CDAC is
+	 * read before the DMA controller finished disabling the channel.
+	 */
+	if (!cpu_is_omap15xx())
+		SET_DMA_ERRATA(DMA_ERRATA_3_3);
+}
+
 /*----------------------------------------------------------------------------*/
 
 static int __init omap_init_dma(void)
@@ -2481,6 +2528,9 @@ static int __init omap_init_dma(void)
 		}
 	}
 
+	/* Configure errata handling for all omap's */
+	configure_dma_errata();
+
 	return 0;
 
 out_free:
diff --git a/arch/arm/plat-omap/include/plat/dma.h b/arch/arm/plat-omap/include/plat/dma.h
index 27578f3..5e28d26 100644
--- a/arch/arm/plat-omap/include/plat/dma.h
+++ b/arch/arm/plat-omap/include/plat/dma.h
@@ -285,6 +285,17 @@
 #define DMA_CH_PRIO_HIGH		0x1
 #define DMA_CH_PRIO_LOW			0x0 /* Def */
 
+/* Errata handling */
+#define IS_DMA_ERRATA(id)		(errata &= (id))
+#define SET_DMA_ERRATA(id)		(errata |= (id))
+
+#define DMA_ERRATA_IFRAME_BUFFERING	(1 << 0)
+#define DMA_ERRATA_PARALLEL_CHANNELS	(1 << 1)
+#define DMA_ERRATA_i378			(1 << 2)
+#define DMA_ERRATA_i541			(1 << 3)
+#define DMA_ERRATA_i88			(1 << 4)
+#define DMA_ERRATA_3_3			(1 << 5)
+
 enum omap_dma_burst_mode {
 	OMAP_DMA_DATA_BURST_DIS = 0,
 	OMAP_DMA_DATA_BURST_4,
-- 
1.7.1