arm: mxs: Add LCDIF clock configuration function

This function turns on the LCDIF clock and configures it's frequency. The
dividers settings are calculated within the function and the current
implementation should be fast and accurate.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Stefano Babic <sbabic@denx.de>

arch/arm/cpu/arm926ejs/mxs/clock.c

@@ -325,6 +325,99 @@ void mxs_set_ssp_busclock(unsigned int bus, uint32_t freq)
 		bus, tgtclk, freq);
 }
 
+void mxs_set_lcdclk(uint32_t freq)
+{
+	struct mxs_clkctrl_regs *clkctrl_regs =
+		(struct mxs_clkctrl_regs *)MXS_CLKCTRL_BASE;
+	uint32_t fp, x, k_rest, k_best, x_best, tk;
+	int32_t k_best_l = 999, k_best_t = 0, x_best_l = 0xff, x_best_t = 0xff;
+
+	if (freq == 0)
+		return;
+
+#if defined(CONFIG_MX23)
+	writel(CLKCTRL_CLKSEQ_BYPASS_PIX, &clkctrl_regs->hw_clkctrl_clkseq_clr);
+#elif defined(CONFIG_MX28)
+	writel(CLKCTRL_CLKSEQ_BYPASS_DIS_LCDIF, &clkctrl_regs->hw_clkctrl_clkseq_clr);
+#endif
+
+	/*
+	 *             /               18 \     1       1
+	 * freq kHz = | 480000000 Hz * --  | * --- * ------
+	 *             \                x /     k     1000
+	 *
+	 *      480000000 Hz   18
+	 *      ------------ * --
+	 *        freq kHz      x
+	 * k = -------------------
+	 *             1000
+	 */
+
+	fp = ((PLL_FREQ_KHZ * 1000) / freq) * 18;
+
+	for (x = 18; x <= 35; x++) {
+		tk = fp / x;
+		if ((tk / 1000 == 0) || (tk / 1000 > 255))
+			continue;
+
+		k_rest = tk % 1000;
+
+		if (k_rest < (k_best_l % 1000)) {
+			k_best_l = tk;
+			x_best_l = x;
+		}
+
+		if (k_rest > (k_best_t % 1000)) {
+			k_best_t = tk;
+			x_best_t = x;
+		}
+	}
+
+	if (1000 - (k_best_t % 1000) > (k_best_l % 1000)) {
+		k_best = k_best_l;
+		x_best = x_best_l;
+	} else {
+		k_best = k_best_t;
+		x_best = x_best_t;
+	}
+
+	k_best /= 1000;
+
+#if defined(CONFIG_MX23)
+	writeb(CLKCTRL_FRAC_CLKGATE,
+		&clkctrl_regs->hw_clkctrl_frac0_set[CLKCTRL_FRAC0_PIX]);
+	writeb(CLKCTRL_FRAC_CLKGATE | (x_best & CLKCTRL_FRAC_FRAC_MASK),
+		&clkctrl_regs->hw_clkctrl_frac0[CLKCTRL_FRAC0_PIX]);
+	writeb(CLKCTRL_FRAC_CLKGATE,
+		&clkctrl_regs->hw_clkctrl_frac0_clr[CLKCTRL_FRAC0_PIX]);
+
+	writel(CLKCTRL_PIX_CLKGATE,
+		&clkctrl_regs->hw_clkctrl_pix_set);
+	clrsetbits_le32(&clkctrl_regs->hw_clkctrl_pix,
+			CLKCTRL_PIX_DIV_MASK | CLKCTRL_PIX_CLKGATE,
+			k_best << CLKCTRL_PIX_DIV_OFFSET);
+
+	while (readl(&clkctrl_regs->hw_clkctrl_pix) & CLKCTRL_PIX_BUSY)
+		;
+#elif defined(CONFIG_MX28)
+	writeb(CLKCTRL_FRAC_CLKGATE,
+		&clkctrl_regs->hw_clkctrl_frac1_set[CLKCTRL_FRAC1_PIX]);
+	writeb(CLKCTRL_FRAC_CLKGATE | (x_best & CLKCTRL_FRAC_FRAC_MASK),
+		&clkctrl_regs->hw_clkctrl_frac1[CLKCTRL_FRAC1_PIX]);
+	writeb(CLKCTRL_FRAC_CLKGATE,
+		&clkctrl_regs->hw_clkctrl_frac1_clr[CLKCTRL_FRAC1_PIX]);
+
+	writel(CLKCTRL_DIS_LCDIF_CLKGATE,
+		&clkctrl_regs->hw_clkctrl_lcdif_set);
+	clrsetbits_le32(&clkctrl_regs->hw_clkctrl_lcdif,
+			CLKCTRL_DIS_LCDIF_DIV_MASK | CLKCTRL_DIS_LCDIF_CLKGATE,
+			k_best << CLKCTRL_DIS_LCDIF_DIV_OFFSET);
+
+	while (readl(&clkctrl_regs->hw_clkctrl_lcdif) & CLKCTRL_DIS_LCDIF_BUSY)
+		;
+#endif
+}
+
 uint32_t mxc_get_clock(enum mxc_clock clk)
 {
 	switch (clk) {

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

@@ -59,6 +59,7 @@ uint32_t mxc_get_clock(enum mxc_clock clk);
 void mxs_set_ioclk(enum mxs_ioclock io, uint32_t freq);
 void mxs_set_sspclk(enum mxs_sspclock ssp, uint32_t freq, int xtal);
 void mxs_set_ssp_busclock(unsigned int bus, uint32_t freq);
+void mxs_set_lcdclk(uint32_t freq);
 
 /* Compatibility with the FEC Ethernet driver */
 #define	imx_get_fecclk()	mxc_get_clock(MXC_AHB_CLK)