aspeed: Add support for Clocks needed by MACs

Add support for clocks needed by MACs to ast2500 clock driver.
The clocks are D2-PLL, which is used by both MACs and PCLK_MAC1 and
PCLK_MAC2 for MAC1 and MAC2 respectively.

The rate of D2-PLL is hardcoded to 250MHz -- the value used in Aspeed
SDK. It is not entirely clear from the datasheet how this clock is used
by MACs, so not clear if the rate would ever need to be different. So,
for now, hardcoding it is probably safer.

The rate of PCLK_MAC{1,2} is chosen based on MAC speed selected through
hardware strapping.

So, the network driver would only need to enable these clocks, no need
to configure the rate.

Signed-off-by: Maxim Sloyko <maxims@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 234 insertions, 31 deletions

diff --git a/drivers/clk/aspeed/clk_ast2500.c b/drivers/clk/aspeed/clk_ast2500.c
index 9e4c66e..7b4b5c6 100644
--- a/drivers/clk/aspeed/clk_ast2500.c
+++ b/drivers/clk/aspeed/clk_ast2500.c
@@ -12,16 +12,39 @@
 #include <dm/lists.h>
 #include <dt-bindings/clock/ast2500-scu.h>
 
+/*
+ * MAC Clock Delay settings, taken from Aspeed SDK
+ */
+#define RGMII_TXCLK_ODLY		8
+#define RMII_RXCLK_IDLY		2
+
+/*
+ * TGMII Clock Duty constants, taken from Aspeed SDK
+ */
+#define RGMII2_TXCK_DUTY	0x66
+#define RGMII1_TXCK_DUTY	0x64
+
+#define D2PLL_DEFAULT_RATE	(250 * 1000 * 1000)
+
 DECLARE_GLOBAL_DATA_PTR;
 
 /*
+ * Clock divider/multiplier configuration struct.
  * For H-PLL and M-PLL the formula is
  * (Output Frequency) = CLKIN * ((M + 1) / (N + 1)) / (P + 1)
  * M - Numerator
  * N - Denumerator
  * P - Post Divider
  * They have the same layout in their control register.
+ *
+ * D-PLL and D2-PLL have extra divider (OD + 1), which is not
+ * yet needed and ignored by clock configurations.
  */
+struct ast2500_div_config {
+	unsigned int num;
+	unsigned int denum;
+	unsigned int post_div;
+};
 
 /*
  * Get the rate of the M-PLL clock from input clock frequency and
@@ -143,30 +166,41 @@ static ulong ast2500_clk_get_rate(struct clk *clk)
 	return rate;
 }
 
-static ulong ast2500_configure_ddr(struct ast2500_scu *scu, ulong rate)
+/*
+ * @input_rate - the rate of input clock in Hz
+ * @requested_rate - desired output rate in Hz
+ * @div - this is an IN/OUT parameter, at input all fields of the config
+ * need to be set to their maximum allowed values.
+ * The result (the best config we could find), would also be returned
+ * in this structure.
+ *
+ * @return The clock rate, when the resulting div_config is used.
+ */
+static ulong ast2500_calc_clock_config(ulong input_rate, ulong requested_rate,
+				       struct ast2500_div_config *cfg)
 {
-	ulong clkin = ast2500_get_clkin(scu);
-	u32 mpll_reg;
-
 	/*
-	 * There are not that many combinations of numerator, denumerator
-	 * and post divider, so just brute force the best combination.
-	 * However, to avoid overflow when multiplying, use kHz.
+	 * The assumption is that kHz precision is good enough and
+	 * also enough to avoid overflow when multiplying.
 	 */
-	const ulong clkin_khz = clkin / 1000;
-	const ulong rate_khz = rate / 1000;
-	ulong best_num = 0;
-	ulong best_denum = 0;
-	ulong best_post = 0;
-	ulong delta = rate;
-	ulong num, denum, post;
-
-	for (denum = 0; denum <= SCU_MPLL_DENUM_MASK; ++denum) {
-		for (post = 0; post <= SCU_MPLL_POST_MASK; ++post) {
-			num = (rate_khz * (post + 1) / clkin_khz) * (denum + 1);
-			ulong new_rate_khz = (clkin_khz
-					      * ((num + 1) / (denum + 1)))
-					     / (post + 1);
+	const ulong input_rate_khz = input_rate / 1000;
+	const ulong rate_khz = requested_rate / 1000;
+	const struct ast2500_div_config max_vals = *cfg;
+	struct ast2500_div_config it = { 0, 0, 0 };
+	ulong delta = rate_khz;
+	ulong new_rate_khz = 0;
+
+	for (; it.denum <= max_vals.denum; ++it.denum) {
+		for (it.post_div = 0; it.post_div <= max_vals.post_div;
+		     ++it.post_div) {
+			it.num = (rate_khz * (it.post_div + 1) / input_rate_khz)
+			    * (it.denum + 1);
+			if (it.num > max_vals.num)
+				continue;
+
+			new_rate_khz = (input_rate_khz
+					* ((it.num + 1) / (it.denum + 1)))
+			    / (it.post_div + 1);
 
 			/* Keep the rate below requested one. */
 			if (new_rate_khz > rate_khz)
@@ -174,25 +208,35 @@ static ulong ast2500_configure_ddr(struct ast2500_scu *scu, ulong rate)
 
 			if (new_rate_khz - rate_khz < delta) {
 				delta = new_rate_khz - rate_khz;
-
-				best_num = num;
-				best_denum = denum;
-				best_post = post;
-
+				*cfg = it;
 				if (delta == 0)
-					goto rate_calc_done;
+					return new_rate_khz * 1000;
 			}
 		}
 	}
 
- rate_calc_done:
+	return new_rate_khz * 1000;
+}
+
+static ulong ast2500_configure_ddr(struct ast2500_scu *scu, ulong rate)
+{
+	ulong clkin = ast2500_get_clkin(scu);
+	u32 mpll_reg;
+	struct ast2500_div_config div_cfg = {
+		.num = SCU_MPLL_NUM_MASK,
+		.denum = SCU_MPLL_DENUM_MASK,
+		.post_div = SCU_MPLL_POST_MASK
+	};
+
+	ast2500_calc_clock_config(clkin, rate, &div_cfg);
+
 	mpll_reg = readl(&scu->m_pll_param);
 	mpll_reg &= ~((SCU_MPLL_POST_MASK << SCU_MPLL_POST_SHIFT)
 		      | (SCU_MPLL_NUM_MASK << SCU_MPLL_NUM_SHIFT)
 		      | (SCU_MPLL_DENUM_MASK << SCU_MPLL_DENUM_SHIFT));
-	mpll_reg |= (best_post << SCU_MPLL_POST_SHIFT)
-	    | (best_num << SCU_MPLL_NUM_SHIFT)
-	    | (best_denum << SCU_MPLL_DENUM_SHIFT);
+	mpll_reg |= (div_cfg.post_div << SCU_MPLL_POST_SHIFT)
+	    | (div_cfg.num << SCU_MPLL_NUM_SHIFT)
+	    | (div_cfg.denum << SCU_MPLL_DENUM_SHIFT);
 
 	ast_scu_unlock(scu);
 	writel(mpll_reg, &scu->m_pll_param);
@@ -201,6 +245,136 @@ static ulong ast2500_configure_ddr(struct ast2500_scu *scu, ulong rate)
 	return ast2500_get_mpll_rate(clkin, mpll_reg);
 }
 
+static ulong ast2500_configure_mac(struct ast2500_scu *scu, int index)
+{
+	ulong clkin = ast2500_get_clkin(scu);
+	ulong hpll_rate = ast2500_get_hpll_rate(clkin,
+						readl(&scu->h_pll_param));
+	ulong required_rate;
+	u32 hwstrap;
+	u32 divisor;
+	u32 reset_bit;
+	u32 clkstop_bit;
+
+	/*
+	 * According to data sheet, for 10/100 mode the MAC clock frequency
+	 * should be at least 25MHz and for 1000 mode at least 100MHz
+	 */
+	hwstrap = readl(&scu->hwstrap);
+	if (hwstrap & (SCU_HWSTRAP_MAC1_RGMII | SCU_HWSTRAP_MAC2_RGMII))
+		required_rate = 100 * 1000 * 1000;
+	else
+		required_rate = 25 * 1000 * 1000;
+
+	divisor = hpll_rate / required_rate;
+
+	if (divisor < 4) {
+		/* Clock can't run fast enough, but let's try anyway */
+		debug("MAC clock too slow\n");
+		divisor = 4;
+	} else if (divisor > 16) {
+		/* Can't slow down the clock enough, but let's try anyway */
+		debug("MAC clock too fast\n");
+		divisor = 16;
+	}
+
+	switch (index) {
+	case 1:
+		reset_bit = SCU_SYSRESET_MAC1;
+		clkstop_bit = SCU_CLKSTOP_MAC1;
+		break;
+	case 2:
+		reset_bit = SCU_SYSRESET_MAC2;
+		clkstop_bit = SCU_CLKSTOP_MAC2;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ast_scu_unlock(scu);
+	clrsetbits_le32(&scu->clk_sel1, SCU_MACCLK_MASK,
+			((divisor - 2) / 2) << SCU_MACCLK_SHIFT);
+
+	/*
+	 * Disable MAC, start its clock and re-enable it.
+	 * The procedure and the delays (100us & 10ms) are
+	 * specified in the datasheet.
+	 */
+	setbits_le32(&scu->sysreset_ctrl1, reset_bit);
+	udelay(100);
+	clrbits_le32(&scu->clk_stop_ctrl1, clkstop_bit);
+	mdelay(10);
+	clrbits_le32(&scu->sysreset_ctrl1, reset_bit);
+
+	writel((RGMII2_TXCK_DUTY << SCU_CLKDUTY_RGMII2TXCK_SHIFT)
+	       | (RGMII1_TXCK_DUTY << SCU_CLKDUTY_RGMII1TXCK_SHIFT),
+	       &scu->clk_duty_sel);
+
+	ast_scu_lock(scu);
+
+	return required_rate;
+}
+
+static ulong ast2500_configure_d2pll(struct ast2500_scu *scu, ulong rate)
+{
+	/*
+	 * The values and the meaning of the next three
+	 * parameters are undocumented. Taken from Aspeed SDK.
+	 */
+	const u32 d2_pll_ext_param = 0x2c;
+	const u32 d2_pll_sip = 0x11;
+	const u32 d2_pll_sic = 0x18;
+	u32 clk_delay_settings =
+	    (RMII_RXCLK_IDLY << SCU_MICDS_MAC1RMII_RDLY_SHIFT)
+	    | (RMII_RXCLK_IDLY << SCU_MICDS_MAC2RMII_RDLY_SHIFT)
+	    | (RGMII_TXCLK_ODLY << SCU_MICDS_MAC1RGMII_TXDLY_SHIFT)
+	    | (RGMII_TXCLK_ODLY << SCU_MICDS_MAC2RGMII_TXDLY_SHIFT);
+	struct ast2500_div_config div_cfg = {
+		.num = SCU_D2PLL_NUM_MASK >> SCU_D2PLL_NUM_SHIFT,
+		.denum = SCU_D2PLL_DENUM_MASK >> SCU_D2PLL_DENUM_SHIFT,
+		.post_div = SCU_D2PLL_POST_MASK >> SCU_D2PLL_POST_SHIFT,
+	};
+	ulong clkin = ast2500_get_clkin(scu);
+	ulong new_rate;
+
+	ast_scu_unlock(scu);
+	writel((d2_pll_ext_param << SCU_D2PLL_EXT1_PARAM_SHIFT)
+	       | SCU_D2PLL_EXT1_OFF
+	       | SCU_D2PLL_EXT1_RESET, &scu->d2_pll_ext_param[0]);
+
+	/*
+	 * Select USB2.0 port1 PHY clock as a clock source for GCRT.
+	 * This would disconnect it from D2-PLL.
+	 */
+	clrsetbits_le32(&scu->misc_ctrl1, SCU_MISC_D2PLL_OFF,
+			SCU_MISC_GCRT_USB20CLK);
+
+	new_rate = ast2500_calc_clock_config(clkin, rate, &div_cfg);
+	writel((d2_pll_sip << SCU_D2PLL_SIP_SHIFT)
+	       | (d2_pll_sic << SCU_D2PLL_SIC_SHIFT)
+	       | (div_cfg.num << SCU_D2PLL_NUM_SHIFT)
+	       | (div_cfg.denum << SCU_D2PLL_DENUM_SHIFT)
+	       | (div_cfg.post_div << SCU_D2PLL_POST_SHIFT),
+	       &scu->d2_pll_param);
+
+	clrbits_le32(&scu->d2_pll_ext_param[0],
+		     SCU_D2PLL_EXT1_OFF | SCU_D2PLL_EXT1_RESET);
+
+	clrsetbits_le32(&scu->misc_ctrl2,
+			SCU_MISC2_RGMII_HPLL | SCU_MISC2_RMII_MPLL
+			| SCU_MISC2_RGMII_CLKDIV_MASK |
+			SCU_MISC2_RMII_CLKDIV_MASK,
+			(4 << SCU_MISC2_RMII_CLKDIV_SHIFT));
+
+	writel(clk_delay_settings | SCU_MICDS_RGMIIPLL, &scu->mac_clk_delay);
+	writel(clk_delay_settings, &scu->mac_clk_delay_100M);
+	writel(clk_delay_settings, &scu->mac_clk_delay_10M);
+
+	ast_scu_lock(scu);
+
+	return new_rate;
+}
+
 static ulong ast2500_clk_set_rate(struct clk *clk, ulong rate)
 {
 	struct ast2500_clk_priv *priv = dev_get_priv(clk->dev);
@@ -211,6 +385,9 @@ static ulong ast2500_clk_set_rate(struct clk *clk, ulong rate)
 	case MCLK_DDR:
 		new_rate = ast2500_configure_ddr(priv->scu, rate);
 		break;
+	case PLL_D2PLL:
+		new_rate = ast2500_configure_d2pll(priv->scu, rate);
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -218,9 +395,35 @@ static ulong ast2500_clk_set_rate(struct clk *clk, ulong rate)
 	return new_rate;
 }
 
+static int ast2500_clk_enable(struct clk *clk)
+{
+	struct ast2500_clk_priv *priv = dev_get_priv(clk->dev);
+
+	switch (clk->id) {
+	/*
+	 * For MAC clocks the clock rate is
+	 * configured based on whether RGMII or RMII mode has been selected
+	 * through hardware strapping.
+	 */
+	case PCLK_MAC1:
+		ast2500_configure_mac(priv->scu, 1);
+		break;
+	case PCLK_MAC2:
+		ast2500_configure_mac(priv->scu, 2);
+		break;
+	case PLL_D2PLL:
+		ast2500_configure_d2pll(priv->scu, D2PLL_DEFAULT_RATE);
+	default:
+		return -ENOENT;
+	}
+
+	return 0;
+}
+
 struct clk_ops ast2500_clk_ops = {
 	.get_rate = ast2500_clk_get_rate,
 	.set_rate = ast2500_clk_set_rate,
+	.enable = ast2500_clk_enable,
 };
 
 static int ast2500_clk_probe(struct udevice *dev)