Re: [PATCH 3/4] OMAP3 McSPI: Adds context save/restore

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Hello,
I'm afraid this patch needs more work. The optimized restoration of chconf can cause occasionally errors with off mode if multiple chip selects are in use. In practice it is needed to restore all CHxCONF registers, not just the one by a specific chip select. 

ext Kevin Hilman wrote:

From: Hemanth V <hemanthv@xxxxxx>

This patch adds context save/restore feature to McSPI driver.
This includes fixes by Aaro Koskinen

Signed-off-by: Hemanth V <hemanthv@xxxxxx>
Reviewed-by: Aaro Koskinen <Aaro.Koskinen@xxxxxxxxx>
Signed-off-by: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>
---
 drivers/spi/omap2_mcspi.c |  134 +++++++++++++++++++++++++++++++++-----------
 1 files changed, 100 insertions(+), 34 deletions(-)

diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
index 0016078..5240c01 100644
--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -41,6 +41,9 @@
#define OMAP2_MCSPI_MAX_FREQ 48000000 +/* OMAP2 has 3 SPI controllers, while OMAP3 has 4 */ 
+#define OMAP2_MCSPI_MAX_CTRL 		4
+
 #define OMAP2_MCSPI_REVISION		0x00
 #define OMAP2_MCSPI_SYSCONFIG		0x10
 #define OMAP2_MCSPI_SYSSTATUS		0x14
@@ -131,8 +134,21 @@ struct omap2_mcspi_cs {
 	void __iomem		*base;
 	unsigned long		phys;
 	int			word_len;
+	/* Context save and restore shadow register */
+	u32			chconf0;
+};
+
+/* used for context save and restore, structure members to be updated whenever
+ * corresponding registers are modified.
+ */
+struct omap2_mcspi_regs {
+	u32 sysconfig;
+	u32 modulctrl;
+	u32 wakeupenable;
 };
+static struct omap2_mcspi_regs omap2_mcspi_ctx[OMAP2_MCSPI_MAX_CTRL]; 
+
 static struct workqueue_struct *omap2_mcspi_wq;
#define MOD_REG_BIT(val, mask, set) do { \ 
@@ -172,12 +188,27 @@ static inline u32 mcspi_read_cs_reg(const struct spi_device *spi, int idx)
 	return __raw_readl(cs->base + idx);
 }
+static inline u32 mcspi_cached_chconf0(const struct spi_device *spi) 
+{
+	struct omap2_mcspi_cs *cs = spi->controller_state;
+
+	return cs->chconf0;
+}
+
+static inline void mcspi_write_chconf0(const struct spi_device *spi, u32 val)
+{
+	struct omap2_mcspi_cs *cs = spi->controller_state;
+
+	cs->chconf0 = val;
+	mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCONF0, val);
+}
+
 static void omap2_mcspi_set_dma_req(const struct spi_device *spi,
 		int is_read, int enable)
 {
 	u32 l, rw;
- l = mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHCONF0); 
+	l = mcspi_cached_chconf0(spi);
if (is_read) /* 1 is read, 0 write */ 
 		rw = OMAP2_MCSPI_CHCONF_DMAR;
@@ -185,7 +216,7 @@ static void omap2_mcspi_set_dma_req(const struct spi_device *spi,
 		rw = OMAP2_MCSPI_CHCONF_DMAW;
MOD_REG_BIT(l, rw, enable); 
-	mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCONF0, l);
+	mcspi_write_chconf0(spi, l);
 }
static void omap2_mcspi_set_enable(const struct spi_device *spi, int enable) 
@@ -200,9 +231,9 @@ static void omap2_mcspi_force_cs(struct spi_device *spi, int cs_active)
 {
 	u32 l;
- l = mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHCONF0); 
+	l = mcspi_cached_chconf0(spi);
 	MOD_REG_BIT(l, OMAP2_MCSPI_CHCONF_FORCE, cs_active);
-	mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCONF0, l);
+	mcspi_write_chconf0(spi, l);
 }
static void omap2_mcspi_set_master_mode(struct spi_master *master) 
@@ -217,6 +248,41 @@ static void omap2_mcspi_set_master_mode(struct spi_master *master)
 	MOD_REG_BIT(l, OMAP2_MCSPI_MODULCTRL_MS, 0);
 	MOD_REG_BIT(l, OMAP2_MCSPI_MODULCTRL_SINGLE, 1);
 	mcspi_write_reg(master, OMAP2_MCSPI_MODULCTRL, l);
+
+	omap2_mcspi_ctx[master->bus_num - 1].modulctrl = l;
+}
+
+static void omap2_mcspi_restore_ctx(struct omap2_mcspi *mcspi)
+{
+	struct spi_master *spi_cntrl;
+	spi_cntrl = mcspi->master;
+
+	/* McSPI: context restore */
+	mcspi_write_reg(spi_cntrl, OMAP2_MCSPI_MODULCTRL,
+			omap2_mcspi_ctx[spi_cntrl->bus_num - 1].modulctrl);
+
+	mcspi_write_reg(spi_cntrl, OMAP2_MCSPI_SYSCONFIG,
+			omap2_mcspi_ctx[spi_cntrl->bus_num - 1].sysconfig);
+
+	mcspi_write_reg(spi_cntrl, OMAP2_MCSPI_WAKEUPENABLE,
+			omap2_mcspi_ctx[spi_cntrl->bus_num - 1].wakeupenable);
+}
+static void omap2_mcspi_disable_clocks(struct omap2_mcspi *mcspi)
+{
+	clk_disable(mcspi->ick);
+	clk_disable(mcspi->fck);
+}
+
+static int omap2_mcspi_enable_clocks(struct omap2_mcspi *mcspi)
+{
+	if (clk_enable(mcspi->ick))
+		return -ENODEV;
+	if (clk_enable(mcspi->fck))
+		return -ENODEV;
+
+	omap2_mcspi_restore_ctx(mcspi);
+
+	return 0;
 }
static unsigned 
@@ -338,7 +404,7 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
 	c = count;
 	word_len = cs->word_len;
- l = mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHCONF0); 
+	l = mcspi_cached_chconf0(spi);
 	l &= ~OMAP2_MCSPI_CHCONF_TRM_MASK;
/* We store the pre-calculated register addresses on stack to speed 
@@ -378,8 +444,7 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
 				 * more word i/o: switch to rx+tx
 				 */
 				if (c == 0 && tx == NULL)
-					mcspi_write_cs_reg(spi,
-							OMAP2_MCSPI_CHCONF0, l);
+					mcspi_write_chconf0(spi, l);
 				*rx++ = __raw_readl(rx_reg);
 #ifdef VERBOSE
 				dev_dbg(&spi->dev, "read-%d %02x\n",
@@ -417,8 +482,7 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
 				 * more word i/o: switch to rx+tx
 				 */
 				if (c == 0 && tx == NULL)
-					mcspi_write_cs_reg(spi,
-							OMAP2_MCSPI_CHCONF0, l);
+					mcspi_write_chconf0(spi, l);
 				*rx++ = __raw_readl(rx_reg);
 #ifdef VERBOSE
 				dev_dbg(&spi->dev, "read-%d %04x\n",
@@ -456,8 +520,7 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
 				 * more word i/o: switch to rx+tx
 				 */
 				if (c == 0 && tx == NULL)
-					mcspi_write_cs_reg(spi,
-							OMAP2_MCSPI_CHCONF0, l);
+					mcspi_write_chconf0(spi, l);
 				*rx++ = __raw_readl(rx_reg);
 #ifdef VERBOSE
 				dev_dbg(&spi->dev, "read-%d %04x\n",
@@ -486,10 +549,12 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
 {
 	struct omap2_mcspi_cs *cs = spi->controller_state;
 	struct omap2_mcspi *mcspi;
+	struct spi_master *spi_cntrl;
 	u32 l = 0, div = 0;
 	u8 word_len = spi->bits_per_word;
mcspi = spi_master_get_devdata(spi->master); 
+	spi_cntrl = mcspi->master;
if (t != NULL && t->bits_per_word) 
 		word_len = t->bits_per_word;
@@ -503,7 +568,7 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
 	} else
 		div = 15;
- l = mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHCONF0); 
+	l = mcspi_cached_chconf0(spi);
/* standard 4-wire master mode: SCK, MOSI/out, MISO/in, nCS 
 	 * REVISIT: this controller could support SPI_3WIRE mode.
@@ -535,7 +600,7 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
 	else
 		l &= ~OMAP2_MCSPI_CHCONF_PHA;
- mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCONF0, l); 
+	mcspi_write_chconf0(spi, l);
dev_dbg(&spi->dev, "setup: speed %d, sample %s edge, clk %s\n", 
 			OMAP2_MCSPI_MAX_FREQ / (1 << div),
@@ -628,6 +693,7 @@ static int omap2_mcspi_setup(struct spi_device *spi)
 			return -ENOMEM;
 		cs->base = mcspi->base + spi->chip_select * 0x14;
 		cs->phys = mcspi->phys + spi->chip_select * 0x14;
+		cs->chconf0 = 0;
 		spi->controller_state = cs;
 	}
@@ -638,11 +704,11 @@ static int omap2_mcspi_setup(struct spi_device *spi) 
 			return ret;
 	}
- clk_enable(mcspi->ick); 
-	clk_enable(mcspi->fck);
+	if (omap2_mcspi_enable_clocks(mcspi))
+		return -ENODEV;
+
 	ret = omap2_mcspi_setup_transfer(spi, NULL);
-	clk_disable(mcspi->fck);
-	clk_disable(mcspi->ick);
+	omap2_mcspi_disable_clocks(mcspi);
return ret; 
 }
@@ -674,8 +740,8 @@ static void omap2_mcspi_work(struct work_struct *work)
 	mcspi = container_of(work, struct omap2_mcspi, work);
 	spin_lock_irq(&mcspi->lock);
- clk_enable(mcspi->ick); 
-	clk_enable(mcspi->fck);
+	if (omap2_mcspi_enable_clocks(mcspi))
+		goto out;
/* We only enable one channel at a time -- the one whose message is 
 	 * at the head of the queue -- although this controller would gladly
@@ -722,13 +788,13 @@ static void omap2_mcspi_work(struct work_struct *work)
 				cs_active = 1;
 			}
- chconf = mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHCONF0); 
+			chconf = mcspi_cached_chconf0(spi);
 			chconf &= ~OMAP2_MCSPI_CHCONF_TRM_MASK;
 			if (t->tx_buf == NULL)
 				chconf |= OMAP2_MCSPI_CHCONF_TRM_RX_ONLY;
 			else if (t->rx_buf == NULL)
 				chconf |= OMAP2_MCSPI_CHCONF_TRM_TX_ONLY;
-			mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCONF0, chconf);
+			mcspi_write_chconf0(spi, chconf);
if (t->len) { 
 				unsigned	count;
@@ -777,9 +843,9 @@ static void omap2_mcspi_work(struct work_struct *work)
 		spin_lock_irq(&mcspi->lock);
 	}
- clk_disable(mcspi->fck); 
-	clk_disable(mcspi->ick);
+	omap2_mcspi_disable_clocks(mcspi);
+out: 
 	spin_unlock_irq(&mcspi->lock);
 }
@@ -866,8 +932,8 @@ static int __init omap2_mcspi_reset(struct omap2_mcspi *mcspi) 
 	struct spi_master	*master = mcspi->master;
 	u32			tmp;
- clk_enable(mcspi->ick); 
-	clk_enable(mcspi->fck);
+	if (omap2_mcspi_enable_clocks(mcspi))
+		return -1;
mcspi_write_reg(master, OMAP2_MCSPI_SYSCONFIG, 
 			OMAP2_MCSPI_SYSCONFIG_SOFTRESET);
@@ -875,18 +941,18 @@ static int __init omap2_mcspi_reset(struct omap2_mcspi *mcspi)
 		tmp = mcspi_read_reg(master, OMAP2_MCSPI_SYSSTATUS);
 	} while (!(tmp & OMAP2_MCSPI_SYSSTATUS_RESETDONE));
- mcspi_write_reg(master, OMAP2_MCSPI_SYSCONFIG, 
-			OMAP2_MCSPI_SYSCONFIG_AUTOIDLE |
-			OMAP2_MCSPI_SYSCONFIG_ENAWAKEUP |
-			OMAP2_MCSPI_SYSCONFIG_SMARTIDLE);
+	tmp = OMAP2_MCSPI_SYSCONFIG_AUTOIDLE |
+		OMAP2_MCSPI_SYSCONFIG_ENAWAKEUP |
+		OMAP2_MCSPI_SYSCONFIG_SMARTIDLE;
+	mcspi_write_reg(master, OMAP2_MCSPI_SYSCONFIG, tmp);
+	omap2_mcspi_ctx[master->bus_num - 1].sysconfig = tmp;
- mcspi_write_reg(master, OMAP2_MCSPI_WAKEUPENABLE, 
-			OMAP2_MCSPI_WAKEUPENABLE_WKEN);
+	tmp = OMAP2_MCSPI_WAKEUPENABLE_WKEN;
+	mcspi_write_reg(master, OMAP2_MCSPI_WAKEUPENABLE, tmp);
+	omap2_mcspi_ctx[master->bus_num - 1].wakeupenable = tmp;
omap2_mcspi_set_master_mode(master); 
-
-	clk_disable(mcspi->fck);
-	clk_disable(mcspi->ick);
+	omap2_mcspi_disable_clocks(mcspi);
 	return 0;
 }


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