phy: phy-brcm-sata: Allow configuration SATA AFE TX amplitude

Read the 'brcm,tx-amplitude-millivolt' property from Device Tree and
propagate its value into the appropriate test transmit register to
change the TX amplitude.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20201022205056.233879-3-f.fainelli@gmail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/broadcom/phy-brcm-sata.c

@@ -65,6 +65,7 @@ struct brcm_sata_port {
 	bool ssc_en;
 	enum brcm_sata_phy_rxaeq_mode rxaeq_mode;
 	u32 rxaeq_val;
+	u32 tx_amplitude_val;
 };
 
 struct brcm_sata_phy {
@@ -84,6 +85,10 @@ enum sata_phy_regs {
 	BLOCK0_SPARE_OOB_CLK_SEL_MASK		= 0x3,
 	BLOCK0_SPARE_OOB_CLK_SEL_REFBY2		= 0x1,
 
+	BLOCK1_REG_BANK				= 0x10,
+	BLOCK1_TEST_TX				= 0x83,
+	BLOCK1_TEST_TX_AMP_SHIFT		= 12,
+
 	PLL_REG_BANK_0				= 0x050,
 	PLL_REG_BANK_0_PLLCONTROL_0		= 0x81,
 	PLLCONTROL_0_FREQ_DET_RESTART		= BIT(13),
@@ -379,6 +384,29 @@ static int brcm_stb_sata_16nm_ssc_init(struct brcm_sata_port *port)
 	brcm_sata_phy_wr(port, RXPMD_REG_BANK, RXPMD_RX_FREQ_MON_CONTROL1,
 			 ~tmp, RXPMD_MON_CORRECT_EN | value);
 
+	tmp = GENMASK(15, 12);
+	switch (port->tx_amplitude_val) {
+	case 400:
+		value = BIT(12) | BIT(13);
+		break;
+	case 500:
+		value = BIT(13);
+		break;
+	case 600:
+		value = BIT(12);
+		break;
+	case 800:
+		value = 0;
+		break;
+	default:
+		value = tmp;
+		break;
+	}
+
+	if (value != tmp)
+		brcm_sata_phy_wr(port, BLOCK1_REG_BANK, BLOCK1_TEST_TX, ~tmp,
+				 value);
+
 	/* Turn on/off SSC */
 	brcm_sata_phy_wr(port, TX_REG_BANK, TX_ACTRL5, ~TX_ACTRL5_SSC_EN,
 			 port->ssc_en ? TX_ACTRL5_SSC_EN : 0);
@@ -787,6 +815,10 @@ static int brcm_sata_phy_probe(struct platform_device *pdev)
 		if (port->rxaeq_mode == RXAEQ_MODE_MANUAL)
 			of_property_read_u32(child, "brcm,rxaeq-value",
 					     &port->rxaeq_val);
+
+		of_property_read_u32(child, "brcm,tx-amplitude-millivolt",
+				     &port->tx_amplitude_val);
+
 		port->ssc_en = of_property_read_bool(child, "brcm,enable-ssc");
 		if (IS_ERR(port->phy)) {
 			dev_err(dev, "failed to create PHY\n");