--- /dev/null
+/*
+ * Copyright (C) 2014 STMicroelectronics – All Rights Reserved
+ *
+ * STMicroelectronics PHY driver MiPHY365 (for SoC STiH416).
+ *
+ * Authors: Alexandre Torgue <alexandre.torgue@st.com>
+ * Lee Jones <lee.jones@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/of_address.h>
+#include <linux/clk.h>
+#include <linux/phy/phy.h>
+#include <linux/delay.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+
+#include <dt-bindings/phy/phy.h>
+
+#define HFC_TIMEOUT 100
+
+#define SYSCFG_SELECT_SATA_MASK BIT(1)
+#define SYSCFG_SELECT_SATA_POS 1
+
+/* MiPHY365x register definitions */
+#define RESET_REG 0x00
+#define RST_PLL BIT(1)
+#define RST_PLL_CAL BIT(2)
+#define RST_RX BIT(4)
+#define RST_MACRO BIT(7)
+
+#define STATUS_REG 0x01
+#define IDLL_RDY BIT(0)
+#define PLL_RDY BIT(1)
+#define DES_BIT_LOCK BIT(2)
+#define DES_SYMBOL_LOCK BIT(3)
+
+#define CTRL_REG 0x02
+#define TERM_EN BIT(0)
+#define PCI_EN BIT(2)
+#define DES_BIT_LOCK_EN BIT(3)
+#define TX_POL BIT(5)
+
+#define INT_CTRL_REG 0x03
+
+#define BOUNDARY1_REG 0x10
+#define SPDSEL_SEL BIT(0)
+
+#define BOUNDARY3_REG 0x12
+#define TX_SPDSEL_GEN1_VAL 0
+#define TX_SPDSEL_GEN2_VAL 0x01
+#define TX_SPDSEL_GEN3_VAL 0x02
+#define RX_SPDSEL_GEN1_VAL 0
+#define RX_SPDSEL_GEN2_VAL (0x01 << 3)
+#define RX_SPDSEL_GEN3_VAL (0x02 << 3)
+
+#define PCIE_REG 0x16
+
+#define BUF_SEL_REG 0x20
+#define CONF_GEN_SEL_GEN3 0x02
+#define CONF_GEN_SEL_GEN2 0x01
+#define PD_VDDTFILTER BIT(4)
+
+#define TXBUF1_REG 0x21
+#define SWING_VAL 0x04
+#define SWING_VAL_GEN1 0x03
+#define PREEMPH_VAL (0x3 << 5)
+
+#define TXBUF2_REG 0x22
+#define TXSLEW_VAL 0x2
+#define TXSLEW_VAL_GEN1 0x4
+
+#define RXBUF_OFFSET_CTRL_REG 0x23
+
+#define RXBUF_REG 0x25
+#define SDTHRES_VAL 0x01
+#define EQ_ON3 (0x03 << 4)
+#define EQ_ON1 (0x01 << 4)
+
+#define COMP_CTRL1_REG 0x40
+#define START_COMSR BIT(0)
+#define START_COMZC BIT(1)
+#define COMSR_DONE BIT(2)
+#define COMZC_DONE BIT(3)
+#define COMP_AUTO_LOAD BIT(4)
+
+#define COMP_CTRL2_REG 0x41
+#define COMP_2MHZ_RAT_GEN1 0x1e
+#define COMP_2MHZ_RAT 0xf
+
+#define COMP_CTRL3_REG 0x42
+#define COMSR_COMP_REF 0x33
+
+#define COMP_IDLL_REG 0x47
+#define COMZC_IDLL 0x2a
+
+#define PLL_CTRL1_REG 0x50
+#define PLL_START_CAL BIT(0)
+#define BUF_EN BIT(2)
+#define SYNCHRO_TX BIT(3)
+#define SSC_EN BIT(6)
+#define CONFIG_PLL BIT(7)
+
+#define PLL_CTRL2_REG 0x51
+#define BYPASS_PLL_CAL BIT(1)
+
+#define PLL_RAT_REG 0x52
+
+#define PLL_SSC_STEP_MSB_REG 0x56
+#define PLL_SSC_STEP_MSB_VAL 0x03
+
+#define PLL_SSC_STEP_LSB_REG 0x57
+#define PLL_SSC_STEP_LSB_VAL 0x63
+
+#define PLL_SSC_PER_MSB_REG 0x58
+#define PLL_SSC_PER_MSB_VAL 0
+
+#define PLL_SSC_PER_LSB_REG 0x59
+#define PLL_SSC_PER_LSB_VAL 0xf1
+
+#define IDLL_TEST_REG 0x72
+#define START_CLK_HF BIT(6)
+
+#define DES_BITLOCK_REG 0x86
+#define BIT_LOCK_LEVEL 0x01
+#define BIT_LOCK_CNT_512 (0x03 << 5)
+
+struct miphy365x_phy {
+ struct phy *phy;
+ void __iomem *base;
+ bool pcie_tx_pol_inv;
+ bool sata_tx_pol_inv;
+ u32 sata_gen;
+ u32 ctrlreg;
+ u8 type;
+};
+
+struct miphy365x_dev {
+ struct device *dev;
+ struct regmap *regmap;
+ struct mutex miphy_mutex;
+ struct miphy365x_phy **phys;
+ int nphys;
+};
+
+/*
+ * These values are represented in Device tree. They are considered to be ABI
+ * and although they can be extended any existing values must not change.
+ */
+enum miphy_sata_gen {
+ SATA_GEN1 = 1,
+ SATA_GEN2,
+ SATA_GEN3
+};
+
+static u8 rx_tx_spd[] = {
+ 0, /* GEN0 doesn't exist. */
+ TX_SPDSEL_GEN1_VAL | RX_SPDSEL_GEN1_VAL,
+ TX_SPDSEL_GEN2_VAL | RX_SPDSEL_GEN2_VAL,
+ TX_SPDSEL_GEN3_VAL | RX_SPDSEL_GEN3_VAL
+};
+
+/*
+ * This function selects the system configuration,
+ * either two SATA, one SATA and one PCIe, or two PCIe lanes.
+ */
+static int miphy365x_set_path(struct miphy365x_phy *miphy_phy,
+ struct miphy365x_dev *miphy_dev)
+{
+ bool sata = (miphy_phy->type == PHY_TYPE_SATA);
+
+ return regmap_update_bits(miphy_dev->regmap,
+ miphy_phy->ctrlreg,
+ SYSCFG_SELECT_SATA_MASK,
+ sata << SYSCFG_SELECT_SATA_POS);
+}
+
+static int miphy365x_init_pcie_port(struct miphy365x_phy *miphy_phy,
+ struct miphy365x_dev *miphy_dev)
+{
+ u8 val;
+
+ if (miphy_phy->pcie_tx_pol_inv) {
+ /* Invert Tx polarity and clear pci_txdetect_pol bit */
+ val = TERM_EN | PCI_EN | DES_BIT_LOCK_EN | TX_POL;
+ writeb_relaxed(val, miphy_phy->base + CTRL_REG);
+ writeb_relaxed(0x00, miphy_phy->base + PCIE_REG);
+ }
+
+ return 0;
+}
+
+static inline int miphy365x_hfc_not_rdy(struct miphy365x_phy *miphy_phy,
+ struct miphy365x_dev *miphy_dev)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(HFC_TIMEOUT);
+ u8 mask = IDLL_RDY | PLL_RDY;
+ u8 regval;
+
+ do {
+ regval = readb_relaxed(miphy_phy->base + STATUS_REG);
+ if (!(regval & mask))
+ return 0;
+
+ usleep_range(2000, 2500);
+ } while (time_before(jiffies, timeout));
+
+ dev_err(miphy_dev->dev, "HFC ready timeout!\n");
+ return -EBUSY;
+}
+
+static inline int miphy365x_rdy(struct miphy365x_phy *miphy_phy,
+ struct miphy365x_dev *miphy_dev)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(HFC_TIMEOUT);
+ u8 mask = IDLL_RDY | PLL_RDY;
+ u8 regval;
+
+ do {
+ regval = readb_relaxed(miphy_phy->base + STATUS_REG);
+ if ((regval & mask) == mask)
+ return 0;
+
+ usleep_range(2000, 2500);
+ } while (time_before(jiffies, timeout));
+
+ dev_err(miphy_dev->dev, "PHY not ready timeout!\n");
+ return -EBUSY;
+}
+
+static inline void miphy365x_set_comp(struct miphy365x_phy *miphy_phy,
+ struct miphy365x_dev *miphy_dev)
+{
+ u8 val, mask;
+
+ if (miphy_phy->sata_gen == SATA_GEN1)
+ writeb_relaxed(COMP_2MHZ_RAT_GEN1,
+ miphy_phy->base + COMP_CTRL2_REG);
+ else
+ writeb_relaxed(COMP_2MHZ_RAT,
+ miphy_phy->base + COMP_CTRL2_REG);
+
+ if (miphy_phy->sata_gen != SATA_GEN3) {
+ writeb_relaxed(COMSR_COMP_REF,
+ miphy_phy->base + COMP_CTRL3_REG);
+ /*
+ * Force VCO current to value defined by address 0x5A
+ * and disable PCIe100Mref bit
+ * Enable auto load compensation for pll_i_bias
+ */
+ writeb_relaxed(BYPASS_PLL_CAL, miphy_phy->base + PLL_CTRL2_REG);
+ writeb_relaxed(COMZC_IDLL, miphy_phy->base + COMP_IDLL_REG);
+ }
+
+ /*
+ * Force restart compensation and enable auto load
+ * for Comzc_Tx, Comzc_Rx and Comsr on macro
+ */
+ val = START_COMSR | START_COMZC | COMP_AUTO_LOAD;
+ writeb_relaxed(val, miphy_phy->base + COMP_CTRL1_REG);
+
+ mask = COMSR_DONE | COMZC_DONE;
+ while ((readb_relaxed(miphy_phy->base + COMP_CTRL1_REG) & mask) != mask)
+ cpu_relax();
+}
+
+static inline void miphy365x_set_ssc(struct miphy365x_phy *miphy_phy,
+ struct miphy365x_dev *miphy_dev)
+{
+ u8 val;
+
+ /*
+ * SSC Settings. SSC will be enabled through Link
+ * SSC Ampl. = 0.4%
+ * SSC Freq = 31KHz
+ */
+ writeb_relaxed(PLL_SSC_STEP_MSB_VAL,
+ miphy_phy->base + PLL_SSC_STEP_MSB_REG);
+ writeb_relaxed(PLL_SSC_STEP_LSB_VAL,
+ miphy_phy->base + PLL_SSC_STEP_LSB_REG);
+ writeb_relaxed(PLL_SSC_PER_MSB_VAL,
+ miphy_phy->base + PLL_SSC_PER_MSB_REG);
+ writeb_relaxed(PLL_SSC_PER_LSB_VAL,
+ miphy_phy->base + PLL_SSC_PER_LSB_REG);
+
+ /* SSC Settings complete */
+ if (miphy_phy->sata_gen == SATA_GEN1) {
+ val = PLL_START_CAL | BUF_EN | SYNCHRO_TX | CONFIG_PLL;
+ writeb_relaxed(val, miphy_phy->base + PLL_CTRL1_REG);
+ } else {
+ val = SSC_EN | PLL_START_CAL | BUF_EN | SYNCHRO_TX | CONFIG_PLL;
+ writeb_relaxed(val, miphy_phy->base + PLL_CTRL1_REG);
+ }
+}
+
+static int miphy365x_init_sata_port(struct miphy365x_phy *miphy_phy,
+ struct miphy365x_dev *miphy_dev)
+{
+ int ret;
+ u8 val;
+
+ /*
+ * Force PHY macro reset, PLL calibration reset, PLL reset
+ * and assert Deserializer Reset
+ */
+ val = RST_PLL | RST_PLL_CAL | RST_RX | RST_MACRO;
+ writeb_relaxed(val, miphy_phy->base + RESET_REG);
+
+ if (miphy_phy->sata_tx_pol_inv)
+ writeb_relaxed(TX_POL, miphy_phy->base + CTRL_REG);
+
+ /*
+ * Force macro1 to use rx_lspd, tx_lspd
+ * Force Rx_Clock on first I-DLL phase
+ * Force Des in HP mode on macro, rx_lspd, tx_lspd for Gen2/3
+ */
+ writeb_relaxed(SPDSEL_SEL, miphy_phy->base + BOUNDARY1_REG);
+ writeb_relaxed(START_CLK_HF, miphy_phy->base + IDLL_TEST_REG);
+ val = rx_tx_spd[miphy_phy->sata_gen];
+ writeb_relaxed(val, miphy_phy->base + BOUNDARY3_REG);
+
+ /* Wait for HFC_READY = 0 */
+ ret = miphy365x_hfc_not_rdy(miphy_phy, miphy_dev);
+ if (ret)
+ return ret;
+
+ /* Compensation Recalibration */
+ miphy365x_set_comp(miphy_phy, miphy_dev);
+
+ switch (miphy_phy->sata_gen) {
+ case SATA_GEN3:
+ /*
+ * TX Swing target 550-600mv peak to peak diff
+ * Tx Slew target 90-110ps rising/falling time
+ * Rx Eq ON3, Sigdet threshold SDTH1
+ */
+ val = PD_VDDTFILTER | CONF_GEN_SEL_GEN3;
+ writeb_relaxed(val, miphy_phy->base + BUF_SEL_REG);
+ val = SWING_VAL | PREEMPH_VAL;
+ writeb_relaxed(val, miphy_phy->base + TXBUF1_REG);
+ writeb_relaxed(TXSLEW_VAL, miphy_phy->base + TXBUF2_REG);
+ writeb_relaxed(0x00, miphy_phy->base + RXBUF_OFFSET_CTRL_REG);
+ val = SDTHRES_VAL | EQ_ON3;
+ writeb_relaxed(val, miphy_phy->base + RXBUF_REG);
+ break;
+ case SATA_GEN2:
+ /*
+ * conf gen sel=0x1 to program Gen2 banked registers
+ * VDDT filter ON
+ * Tx Swing target 550-600mV peak-to-peak diff
+ * Tx Slew target 90-110 ps rising/falling time
+ * RX Equalization ON1, Sigdet threshold SDTH1
+ */
+ writeb_relaxed(CONF_GEN_SEL_GEN2,
+ miphy_phy->base + BUF_SEL_REG);
+ writeb_relaxed(SWING_VAL, miphy_phy->base + TXBUF1_REG);
+ writeb_relaxed(TXSLEW_VAL, miphy_phy->base + TXBUF2_REG);
+ val = SDTHRES_VAL | EQ_ON1;
+ writeb_relaxed(val, miphy_phy->base + RXBUF_REG);
+ break;
+ case SATA_GEN1:
+ /*
+ * conf gen sel = 00b to program Gen1 banked registers
+ * VDDT filter ON
+ * Tx Swing target 500-550mV peak-to-peak diff
+ * Tx Slew target120-140 ps rising/falling time
+ */
+ writeb_relaxed(PD_VDDTFILTER, miphy_phy->base + BUF_SEL_REG);
+ writeb_relaxed(SWING_VAL_GEN1, miphy_phy->base + TXBUF1_REG);
+ writeb_relaxed(TXSLEW_VAL_GEN1, miphy_phy->base + TXBUF2_REG);
+ break;
+ default:
+ break;
+ }
+
+ /* Force Macro1 in partial mode & release pll cal reset */
+ writeb_relaxed(RST_RX, miphy_phy->base + RESET_REG);
+ usleep_range(100, 150);
+
+ miphy365x_set_ssc(miphy_phy, miphy_dev);
+
+ /* Wait for phy_ready */
+ ret = miphy365x_rdy(miphy_phy, miphy_dev);
+ if (ret)
+ return ret;
+
+ /*
+ * Enable macro1 to use rx_lspd & tx_lspd
+ * Release Rx_Clock on first I-DLL phase on macro1
+ * Assert deserializer reset
+ * des_bit_lock_en is set
+ * bit lock detection strength
+ * Deassert deserializer reset
+ */
+ writeb_relaxed(0x00, miphy_phy->base + BOUNDARY1_REG);
+ writeb_relaxed(0x00, miphy_phy->base + IDLL_TEST_REG);
+ writeb_relaxed(RST_RX, miphy_phy->base + RESET_REG);
+ val = miphy_phy->sata_tx_pol_inv ?
+ (TX_POL | DES_BIT_LOCK_EN) : DES_BIT_LOCK_EN;
+ writeb_relaxed(val, miphy_phy->base + CTRL_REG);
+
+ val = BIT_LOCK_CNT_512 | BIT_LOCK_LEVEL;
+ writeb_relaxed(val, miphy_phy->base + DES_BITLOCK_REG);
+ writeb_relaxed(0x00, miphy_phy->base + RESET_REG);
+
+ return 0;
+}
+
+static int miphy365x_init(struct phy *phy)
+{
+ struct miphy365x_phy *miphy_phy = phy_get_drvdata(phy);
+ struct miphy365x_dev *miphy_dev = dev_get_drvdata(phy->dev.parent);
+ int ret = 0;
+
+ mutex_lock(&miphy_dev->miphy_mutex);
+
+ ret = miphy365x_set_path(miphy_phy, miphy_dev);
+ if (ret) {
+ mutex_unlock(&miphy_dev->miphy_mutex);
+ return ret;
+ }
+
+ /* Initialise Miphy for PCIe or SATA */
+ if (miphy_phy->type == PHY_TYPE_PCIE)
+ ret = miphy365x_init_pcie_port(miphy_phy, miphy_dev);
+ else
+ ret = miphy365x_init_sata_port(miphy_phy, miphy_dev);
+
+ mutex_unlock(&miphy_dev->miphy_mutex);
+
+ return ret;
+}
+
+int miphy365x_get_addr(struct device *dev, struct miphy365x_phy *miphy_phy,
+ int index)
+{
+ struct device_node *phynode = miphy_phy->phy->dev.of_node;
+ const char *name;
+ int type = miphy_phy->type;
+ int ret;
+
+ ret = of_property_read_string_index(phynode, "reg-names", index, &name);
+ if (ret) {
+ dev_err(dev, "no reg-names property not found\n");
+ return ret;
+ }
+
+ if (!((!strncmp(name, "sata", 4) && type == PHY_TYPE_SATA) ||
+ (!strncmp(name, "pcie", 4) && type == PHY_TYPE_PCIE)))
+ return 0;
+
+ miphy_phy->base = of_iomap(phynode, index);
+ if (!miphy_phy->base) {
+ dev_err(dev, "Failed to map %s\n", phynode->full_name);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static struct phy *miphy365x_xlate(struct device *dev,
+ struct of_phandle_args *args)
+{
+ struct miphy365x_dev *miphy_dev = dev_get_drvdata(dev);
+ struct miphy365x_phy *miphy_phy = NULL;
+ struct device_node *phynode = args->np;
+ int ret, index;
+
+ if (!of_device_is_available(phynode)) {
+ dev_warn(dev, "Requested PHY is disabled\n");
+ return ERR_PTR(-ENODEV);
+ }
+
+ if (args->args_count != 1) {
+ dev_err(dev, "Invalid number of cells in 'phy' property\n");
+ return ERR_PTR(-EINVAL);
+ }
+
+ for (index = 0; index < miphy_dev->nphys; index++)
+ if (phynode == miphy_dev->phys[index]->phy->dev.of_node) {
+ miphy_phy = miphy_dev->phys[index];
+ break;
+ }
+
+ if (!miphy_phy) {
+ dev_err(dev, "Failed to find appropriate phy\n");
+ return ERR_PTR(-EINVAL);
+ }
+
+ miphy_phy->type = args->args[0];
+
+ if (!(miphy_phy->type == PHY_TYPE_SATA ||
+ miphy_phy->type == PHY_TYPE_PCIE)) {
+ dev_err(dev, "Unsupported device type: %d\n", miphy_phy->type);
+ return ERR_PTR(-EINVAL);
+ }
+
+ /* Each port handles SATA and PCIE - third entry is always sysconf. */
+ for (index = 0; index < 3; index++) {
+ ret = miphy365x_get_addr(dev, miphy_phy, index);
+ if (ret < 0)
+ return ERR_PTR(ret);
+ }
+
+ return miphy_phy->phy;
+}
+
+static struct phy_ops miphy365x_ops = {
+ .init = miphy365x_init,
+ .owner = THIS_MODULE,
+};
+
+static int miphy365x_of_probe(struct device_node *phynode,
+ struct miphy365x_phy *miphy_phy)
+{
+ of_property_read_u32(phynode, "st,sata-gen", &miphy_phy->sata_gen);
+ if (!miphy_phy->sata_gen)
+ miphy_phy->sata_gen = SATA_GEN1;
+
+ miphy_phy->pcie_tx_pol_inv =
+ of_property_read_bool(phynode, "st,pcie-tx-pol-inv");
+
+ miphy_phy->sata_tx_pol_inv =
+ of_property_read_bool(phynode, "st,sata-tx-pol-inv");
+
+ return 0;
+}
+
+static int miphy365x_probe(struct platform_device *pdev)
+{
+ struct device_node *child, *np = pdev->dev.of_node;
+ struct miphy365x_dev *miphy_dev;
+ struct phy_provider *provider;
+ struct phy *phy;
+ int ret, port = 0;
+
+ miphy_dev = devm_kzalloc(&pdev->dev, sizeof(*miphy_dev), GFP_KERNEL);
+ if (!miphy_dev)
+ return -ENOMEM;
+
+ miphy_dev->nphys = of_get_child_count(np);
+ miphy_dev->phys = devm_kcalloc(&pdev->dev, miphy_dev->nphys,
+ sizeof(*miphy_dev->phys), GFP_KERNEL);
+ if (!miphy_dev->phys)
+ return -ENOMEM;
+
+ miphy_dev->regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
+ if (IS_ERR(miphy_dev->regmap)) {
+ dev_err(miphy_dev->dev, "No syscfg phandle specified\n");
+ return PTR_ERR(miphy_dev->regmap);
+ }
+
+ miphy_dev->dev = &pdev->dev;
+
+ dev_set_drvdata(&pdev->dev, miphy_dev);
+
+ mutex_init(&miphy_dev->miphy_mutex);
+
+ for_each_child_of_node(np, child) {
+ struct miphy365x_phy *miphy_phy;
+
+ miphy_phy = devm_kzalloc(&pdev->dev, sizeof(*miphy_phy),
+ GFP_KERNEL);
+ if (!miphy_phy)
+ return -ENOMEM;
+
+ miphy_dev->phys[port] = miphy_phy;
+
+ phy = devm_phy_create(&pdev->dev, child, &miphy365x_ops);
+ if (IS_ERR(phy)) {
+ dev_err(&pdev->dev, "failed to create PHY\n");
+ return PTR_ERR(phy);
+ }
+
+ miphy_dev->phys[port]->phy = phy;
+
+ ret = miphy365x_of_probe(child, miphy_phy);
+ if (ret)
+ return ret;
+
+ phy_set_drvdata(phy, miphy_dev->phys[port]);
+
+ port++;
+ /* sysconfig offsets are indexed from 1 */
+ ret = of_property_read_u32_index(np, "st,syscfg", port,
+ &miphy_phy->ctrlreg);
+ if (ret) {
+ dev_err(&pdev->dev, "No sysconfig offset found\n");
+ return ret;
+ }
+ }
+
+ provider = devm_of_phy_provider_register(&pdev->dev, miphy365x_xlate);
+ return PTR_ERR_OR_ZERO(provider);
+}
+
+static const struct of_device_id miphy365x_of_match[] = {
+ { .compatible = "st,miphy365x-phy", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, miphy365x_of_match);
+
+static struct platform_driver miphy365x_driver = {
+ .probe = miphy365x_probe,
+ .driver = {
+ .name = "miphy365x-phy",
+ .of_match_table = miphy365x_of_match,
+ }
+};
+module_platform_driver(miphy365x_driver);
+
+MODULE_AUTHOR("Alexandre Torgue <alexandre.torgue@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics miphy365x driver");
+MODULE_LICENSE("GPL v2");
Code Review / kvmfornfv.git / blobdiff