Subject: [PATCH] Use clock freqency from the device tree to calculate correct MPC5200 PSC clock.

From: Jon Smirl <[email-masked]>
Date: Fri, 07 Aug 2009 14:41:47 -0400

Use clock freqency from the device tree to calculate correct MPC5200 PSC clock.
Previous code had errors or used a constant. This versions computes
the right clock based on the xtal and register settings.
---
 arch/powerpc/include/asm/mpc52xx.h           |    2 +-
 arch/powerpc/platforms/52xx/mpc52xx_common.c |   26 ++++++++++++++++++++++++--
 drivers/spi/mpc52xx_psc_spi.c                |    8 +-------
 sound/soc/fsl/mpc5200_psc_i2s.c              |   11 +----------
 4 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/include/asm/mpc52xx.h b/arch/powerpc/include/asm/mpc52xx.h
index cadd398..1ca8a0e 100644
--- a/arch/powerpc/include/asm/mpc52xx.h
+++ b/arch/powerpc/include/asm/mpc52xx.h
@@ -285,7 +285,7 @@ struct mpc52xx_rtc {
 extern void mpc5200_setup_xlb_arbiter(void);
 extern void mpc52xx_declare_of_platform_devices(void);
 extern void mpc52xx_map_common_devices(void);
-extern int mpc52xx_set_psc_clkdiv(int psc_id, int clkdiv);
+extern int mpc52xx_set_psc_clkdiv(int psc_id, int freq);
 extern unsigned int mpc52xx_get_xtal_freq(struct device_node *node);
 extern void mpc52xx_restart(char *cmd);
 
diff --git a/arch/powerpc/platforms/52xx/mpc52xx_common.c b/arch/powerpc/platforms/52xx/mpc52xx_common.c
index a46bad0..f81fb03 100644
--- a/arch/powerpc/platforms/52xx/mpc52xx_common.c
+++ b/arch/powerpc/platforms/52xx/mpc52xx_common.c
@@ -110,6 +110,8 @@ static struct of_device_id mpc52xx_cdm_ids[] __initdata = {
 	{}
 };
 
+static u32 fsystem; /* fsystem clock on mpc5200 */
+
 /**
  * mpc52xx_map_common_devices: iomap devices required by common code
  */
@@ -117,6 +119,7 @@ void __init
 mpc52xx_map_common_devices(void)
 {
 	struct device_node *np;
+	u32 val;
 
 	/* mpc52xx_wdt is mapped here and used in mpc52xx_restart,
 	 * possibly from a interrupt context. wdt is only implement
@@ -133,8 +136,16 @@ mpc52xx_map_common_devices(void)
 
 	/* Clock Distribution Module, used by PSC clock setting function */
 	np = of_find_matching_node(NULL, mpc52xx_cdm_ids);
+	fsystem = mpc5xxx_get_bus_frequency(np);
 	mpc52xx_cdm = of_iomap(np, 0);
 	of_node_put(np);
+
+	/* compute fsystem, it is either 4 or 8 times the bus freq */
+	val = in_be32(&mpc52xx_cdm->rstcfg);
+	if (val & (1 << 5))
+		fsystem *= 8;
+	else
+		fsystem *= 4;
 }
 
 /**
@@ -143,17 +154,28 @@ mpc52xx_map_common_devices(void)
  * @psc_id: id of psc port; must be 1,2,3 or 6
  * @clkdiv: clock divider value to put into CDM PSC register.
  */
-int mpc52xx_set_psc_clkdiv(int psc_id, int clkdiv)
+int mpc52xx_set_psc_clkdiv(int psc_id, int freq)
 {
 	unsigned long flags;
 	u16 __iomem *reg;
 	u32 val;
-	u32 mask;
+	u32 mask, clkdiv, err;
 	u32 mclken_div;
 
 	if (!mpc52xx_cdm)
 		return -ENODEV;
 
+	/* figure out the closest frequency the hardware can make */
+	clkdiv = fsystem / freq;
+	err = fsystem % freq;
+	if (err > freq / 2)
+		clkdiv++;
+	/* hardware is not very flexible, there will be significant error */
+	/* frequency error = fsystem / clkdiv - freq; */
+
+	/* hardware adds one to the divisor */
+	clkdiv -= 1;
+
 	mclken_div = 0x8000 | (clkdiv & 0x1FF);
 	switch (psc_id) {
 	case 1: reg = &mpc52xx_cdm->mclken_div_psc1; mask = 0x20; break;
diff --git a/drivers/spi/mpc52xx_psc_spi.c b/drivers/spi/mpc52xx_psc_spi.c
index d2a04d6..5c8e621 100644
--- a/drivers/spi/mpc52xx_psc_spi.c
+++ b/drivers/spi/mpc52xx_psc_spi.c
@@ -33,7 +33,6 @@
 struct mpc52xx_psc_spi {
 	/* fsl_spi_platform data */
 	void (*cs_control)(struct spi_device *spi, bool on);
-	u32 sysclk;
 
 	/* driver internal data */
 	struct mpc52xx_psc __iomem *psc;
@@ -313,12 +312,9 @@ static int mpc52xx_psc_spi_port_config(int psc_id, struct mpc52xx_psc_spi *mps)
 {
 	struct mpc52xx_psc __iomem *psc = mps->psc;
 	struct mpc52xx_psc_fifo __iomem *fifo = mps->fifo;
-	u32 mclken_div;
 	int ret = 0;
 
-	/* default sysclk is 512MHz */
-	mclken_div = (mps->sysclk ? mps->sysclk : 512000000) / MCLK;
-	mpc52xx_set_psc_clkdiv(psc_id, mclken_div);
+	mpc52xx_set_psc_clkdiv(psc_id, MCLK);
 
 	/* Reset the PSC into a known state */
 	out_8(&psc->command, MPC52xx_PSC_RST_RX);
@@ -383,12 +379,10 @@ static int __init mpc52xx_psc_spi_do_probe(struct of_device *op, u32 regaddr,
 		dev_warn(&op->dev, "probe called without platform data, no "
 				"cs_control function will be called\n");
 		mps->cs_control = NULL;
-		mps->sysclk = 0;
 		master->bus_num = bus_num;
 		master->num_chipselect = 255;
 	} else {
 		mps->cs_control = pdata->cs_control;
-		mps->sysclk = pdata->sysclk;
 		master->bus_num = pdata->bus_num;
 		master->num_chipselect = pdata->max_chipselect;
 	}
diff --git a/sound/soc/fsl/mpc5200_psc_i2s.c b/sound/soc/fsl/mpc5200_psc_i2s.c
index c58fcde..8de4719 100644
--- a/sound/soc/fsl/mpc5200_psc_i2s.c
+++ b/sound/soc/fsl/mpc5200_psc_i2s.c
@@ -115,7 +115,6 @@ static int psc_i2s_set_sysclk(struct snd_soc_dai *cpu_dai,
 			      int clk_id, unsigned int freq, int dir)
 {
 	struct psc_dma *psc_dma = cpu_dai->private_data;
-	int clkdiv, err;
 
 	dev_dbg(psc_dma->dev, "psc_i2s_set_sysclk(cpu_dai=%p, freq=%u, dir=%i)\n",
 				cpu_dai, freq, dir);
@@ -128,15 +127,7 @@ static int psc_i2s_set_sysclk(struct snd_soc_dai *cpu_dai,
 			psc_dma->sicr &= ~MPC52xx_PSC_SICR_CELLSLAVE;
 			psc_dma->sicr |= MPC52xx_PSC_SICR_GENCLK;
 
-			clkdiv = ppc_proc_freq / freq;
-			err = ppc_proc_freq % freq;
-			if (err > freq / 2)
-				clkdiv++;
-
-			dev_dbg(psc_dma->dev, "psc_i2s_set_sysclk(clkdiv %d freq error=%ldHz)\n",
-					clkdiv, (ppc_proc_freq / clkdiv - freq));
-
-			return mpc52xx_set_psc_clkdiv(psc_dma->id + 1, clkdiv);
+			return mpc52xx_set_psc_clkdiv(psc_dma->id + 1, freq);
 		}
 	}
 	return 0;