tegra20: add clock_set_pllout function

Common practice on Tegra 2 boards is to use the pllp_out4 FO
to generate the ULPI reference clock. For this to work we have
to override the default hardware generated output divider.

This function adds a clean way to do so.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/cpu/tegra20-common/clock.c

@@ -396,6 +396,16 @@ static s8 periph_id_to_internal_id[PERIPH_ID_COUNT] = {
 	NONE(CRAM2),
 };
 
+/* number of clock outputs of a PLL */
+static const u8 pll_num_clkouts[] = {
+	1,	/* PLLC */
+	1,	/* PLLM */
+	4,	/* PLLP */
+	1,	/* PLLA */
+	0,	/* PLLU */
+	0,	/* PLLD */
+};
+
 /*
  * Get the oscillator frequency, from the corresponding hardware configuration
  * field.
@@ -604,6 +614,34 @@ unsigned long clock_get_periph_rate(enum periph_id periph_id,
 		(readl(reg) & OUT_CLK_DIVISOR_MASK) >> OUT_CLK_DIVISOR_SHIFT);
 }
 
+int clock_set_pllout(enum clock_id clkid, enum pll_out_id pllout, unsigned rate)
+{
+	struct clk_pll *pll = get_pll(clkid);
+	int data = 0, div = 0, offset = 0;
+
+	if (!clock_id_is_pll(clkid))
+		return -1;
+
+	if (pllout + 1 > pll_num_clkouts[clkid])
+		return -1;
+
+	div = clk_get_divider(8, pll_rate[clkid], rate);
+
+	if (div < 0)
+		return -1;
+
+	/* out2 and out4 are in the high part of the register */
+	if (pllout == PLL_OUT2 || pllout == PLL_OUT4)
+		offset = 16;
+
+	data = (div << PLL_OUT_RATIO_SHIFT) |
+			PLL_OUT_OVRRIDE | PLL_OUT_CLKEN | PLL_OUT_RSTN;
+	clrsetbits_le32(&pll->pll_out[pllout >> 1],
+			PLL_OUT_RATIO_MASK << offset, data << offset);
+
+	return 0;
+}
+
 /**
  * Find the best available 7.1 format divisor given a parent clock rate and
  * required child clock rate. This function assumes that a second-stage

arch/arm/cpu/tegra20-common/warmboot_avp.c

@@ -214,7 +214,7 @@ void wb_start(void)
 
 	reg = PLLM_OUT1_RSTN_RESET_DISABLE | PLLM_OUT1_CLKEN_ENABLE |
 	      PLLM_OUT1_RATIO_VAL_8;
-	writel(reg, &clkrst->crc_pll[CLOCK_ID_MEMORY].pll_out);
+	writel(reg, &clkrst->crc_pll[CLOCK_ID_MEMORY].pll_out[0]);
 
 	reg = SCLK_SWAKE_FIQ_SRC_PLLM_OUT1 | SCLK_SWAKE_IRQ_SRC_PLLM_OUT1 |
 	      SCLK_SWAKE_RUN_SRC_PLLM_OUT1 | SCLK_SWAKE_IDLE_SRC_PLLM_OUT1 |

arch/arm/include/asm/arch-tegra/clk_rst.h

@@ -27,8 +27,7 @@
 /* PLL registers - there are several PLLs in the clock controller */
 struct clk_pll {
 	uint pll_base;		/* the control register */
-	uint pll_out;		/* output control */
-	uint reserved;
+	uint pll_out[2];	/* output control */
 	uint pll_misc;		/* other misc things */
 };
 
@@ -112,6 +111,14 @@ struct clk_rst_ctlr {
 #define PLL_DIVM_SHIFT		0
 #define PLL_DIVM_MASK		(0x1f << PLL_DIVM_SHIFT)
 
+/* CLK_RST_CONTROLLER_PLLx_OUTx_0 */
+#define PLL_OUT_RSTN		(1 << 0)
+#define PLL_OUT_CLKEN		(1 << 1)
+#define PLL_OUT_OVRRIDE		(1 << 2)
+
+#define PLL_OUT_RATIO_SHIFT	8
+#define PLL_OUT_RATIO_MASK	(0xffU << PLL_OUT_RATIO_SHIFT)
+
 /* CLK_RST_CONTROLLER_PLLx_MISC_0 */
 #define PLL_CPCON_SHIFT		8
 #define PLL_CPCON_MASK		(15U << PLL_CPCON_SHIFT)

arch/arm/include/asm/arch-tegra/clock.h

@@ -57,6 +57,18 @@ enum clock_osc_freq clock_get_osc_freq(void);
 unsigned long clock_start_pll(enum clock_id id, u32 divm, u32 divn,
 		u32 divp, u32 cpcon, u32 lfcon);
 
+/**
+ * Set PLL output frequency
+ *
+ * @param clkid	clock id
+ * @param pllout	pll output id
+ * @param rate		desired output rate
+ *
+ * @return 0 if ok, -1 on error (invalid clock id or no suitable divider)
+ */
+int clock_set_pllout(enum clock_id clkid, enum pll_out_id pllout,
+		unsigned rate);
+
 /**
  * Read low-level parameters of a PLL.
  *

arch/arm/include/asm/arch-tegra20/clock-tables.h

@@ -176,6 +176,13 @@ enum periph_id {
 	PERIPH_ID_NONE = -1,
 };
 
+enum pll_out_id {
+	PLL_OUT1,
+	PLL_OUT2,
+	PLL_OUT3,
+	PLL_OUT4
+};
+
 /* Converts a clock number to a clock register: 0=L, 1=H, 2=U */
 #define PERIPH_REG(id) ((id) >> 5)