[PATCH v7 0/4] Add I2C support for Tegra264

[PATCH v7 0/4] Add I2C support for Tegra264

[Kartik Rajput]

Following series of patches add support for Tegra264 and High Speed (HS)
Mode in i2c-tegra.c driver.

Akhil R (2):
  i2c: tegra: Add HS mode support
  i2c: tegra: Add Tegra264 support

Kartik Rajput (2):
  i2c: tegra: Do not configure DMA if not supported
  i2c: tegra: Add support for SW mutex register

 drivers/i2c/busses/i2c-tegra.c | 159 +++++++++++++++++++++++++++++++++
 1 file changed, 159 insertions(+)

-- 
2.43.0

[PATCH v7 1/4] i2c: tegra: Do not configure DMA if not supported

[Kartik Rajput]

On Tegra264, not all I2C controllers have the necessary interface to
GPC DMA, this causes failures when function tegra_i2c_init_dma()
is called.

Ensure that "dmas" device-tree property is present before initializing
DMA in function tegra_i2c_init_dma().

Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
---
v2 -> v4:
	* Add debug print if DMA is not supported by the I2C controller.
v1 -> v2:
	* Update commit message to clarify that some I2C controllers may
	  not have the necessary interface to GPC DMA.
---
 drivers/i2c/busses/i2c-tegra.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index e533460bccc3..d908e5e3f0af 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -446,6 +446,11 @@ static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev)
 	u32 *dma_buf;
 	int err;
 
+	if (!of_property_present(i2c_dev->dev->of_node, "dmas")) {
+		dev_dbg(i2c_dev->dev, "DMA not available, falling back to PIO\n");
+		return 0;
+	}
+
 	if (IS_VI(i2c_dev))
 		return 0;
 
-- 
2.43.0

[PATCH v7 2/4] i2c: tegra: Add HS mode support

[Kartik Rajput]

From: Akhil R <akhilrajeev@nvidia.com>

Add support for HS (High Speed) mode transfers, which is supported by
Tegra194 onwards.

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
---
v3 -> v5:
	* Set has_hs_mode_support to false for unsupported SoCs.
v2 -> v3:
	* Document tlow_hs_mode and thigh_hs_mode.
v1 -> v2:
	* Document has_hs_mode_support.
	* Add a check to set the frequency to fastmode+ if the device
	  does not support HS mode but the requested frequency is more
	  than fastmode+.
---
 drivers/i2c/busses/i2c-tegra.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index d908e5e3f0af..6f816de8b3af 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -91,6 +91,7 @@
 #define I2C_HEADER_IE_ENABLE			BIT(17)
 #define I2C_HEADER_REPEAT_START			BIT(16)
 #define I2C_HEADER_CONTINUE_XFER		BIT(15)
+#define I2C_HEADER_HS_MODE			BIT(22)
 #define I2C_HEADER_SLAVE_ADDR_SHIFT		1
 
 #define I2C_BUS_CLEAR_CNFG			0x084
@@ -198,6 +199,8 @@ enum msg_end_type {
  * @thigh_std_mode: High period of the clock in standard mode.
  * @tlow_fast_fastplus_mode: Low period of the clock in fast/fast-plus modes.
  * @thigh_fast_fastplus_mode: High period of the clock in fast/fast-plus modes.
+ * @tlow_hs_mode: Low period of the clock in HS mode.
+ * @thigh_hs_mode: High period of the clock in HS mode.
  * @setup_hold_time_std_mode: Setup and hold time for start and stop conditions
  *		in standard mode.
  * @setup_hold_time_fast_fast_plus_mode: Setup and hold time for start and stop
@@ -206,6 +209,7 @@ enum msg_end_type {
  *		in HS mode.
  * @has_interface_timing_reg: Has interface timing register to program the tuned
  *		timing settings.
+ * @has_hs_mode_support: Has support for high speed (HS) mode transfers.
  */
 struct tegra_i2c_hw_feature {
 	bool has_continue_xfer_support;
@@ -226,10 +230,13 @@ struct tegra_i2c_hw_feature {
 	u32 thigh_std_mode;
 	u32 tlow_fast_fastplus_mode;
 	u32 thigh_fast_fastplus_mode;
+	u32 tlow_hs_mode;
+	u32 thigh_hs_mode;
 	u32 setup_hold_time_std_mode;
 	u32 setup_hold_time_fast_fast_plus_mode;
 	u32 setup_hold_time_hs_mode;
 	bool has_interface_timing_reg;
+	bool has_hs_mode_support;
 };
 
 /**
@@ -717,6 +724,20 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
 	if (i2c_dev->hw->has_interface_timing_reg && tsu_thd)
 		i2c_writel(i2c_dev, tsu_thd, I2C_INTERFACE_TIMING_1);
 
+	/* Write HS mode registers. These will get used only for HS mode*/
+	if (i2c_dev->hw->has_hs_mode_support) {
+		tlow = i2c_dev->hw->tlow_hs_mode;
+		thigh = i2c_dev->hw->thigh_hs_mode;
+		tsu_thd = i2c_dev->hw->setup_hold_time_hs_mode;
+
+		val = FIELD_PREP(I2C_HS_INTERFACE_TIMING_THIGH, thigh) |
+			FIELD_PREP(I2C_HS_INTERFACE_TIMING_TLOW, tlow);
+		i2c_writel(i2c_dev, val, I2C_HS_INTERFACE_TIMING_0);
+		i2c_writel(i2c_dev, tsu_thd, I2C_HS_INTERFACE_TIMING_1);
+	} else if (t->bus_freq_hz > I2C_MAX_FAST_MODE_PLUS_FREQ) {
+		t->bus_freq_hz = I2C_MAX_FAST_MODE_PLUS_FREQ;
+	}
+
 	clk_multiplier = (tlow + thigh + 2) * (non_hs_mode + 1);
 
 	err = clk_set_rate(i2c_dev->div_clk,
@@ -1214,6 +1235,9 @@ static void tegra_i2c_push_packet_header(struct tegra_i2c_dev *i2c_dev,
 	if (msg->flags & I2C_M_RD)
 		packet_header |= I2C_HEADER_READ;
 
+	if (i2c_dev->timings.bus_freq_hz > I2C_MAX_FAST_MODE_PLUS_FREQ)
+		packet_header |= I2C_HEADER_HS_MODE;
+
 	if (i2c_dev->dma_mode && !i2c_dev->msg_read)
 		*dma_buf++ = packet_header;
 	else
@@ -1502,6 +1526,7 @@ static const struct tegra_i2c_hw_feature tegra20_i2c_hw = {
 	.setup_hold_time_fast_fast_plus_mode = 0x0,
 	.setup_hold_time_hs_mode = 0x0,
 	.has_interface_timing_reg = false,
+	.has_hs_mode_support = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra30_i2c_hw = {
@@ -1527,6 +1552,7 @@ static const struct tegra_i2c_hw_feature tegra30_i2c_hw = {
 	.setup_hold_time_fast_fast_plus_mode = 0x0,
 	.setup_hold_time_hs_mode = 0x0,
 	.has_interface_timing_reg = false,
+	.has_hs_mode_support = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra114_i2c_hw = {
@@ -1552,6 +1578,7 @@ static const struct tegra_i2c_hw_feature tegra114_i2c_hw = {
 	.setup_hold_time_fast_fast_plus_mode = 0x0,
 	.setup_hold_time_hs_mode = 0x0,
 	.has_interface_timing_reg = false,
+	.has_hs_mode_support = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra124_i2c_hw = {
@@ -1577,6 +1604,7 @@ static const struct tegra_i2c_hw_feature tegra124_i2c_hw = {
 	.setup_hold_time_fast_fast_plus_mode = 0x0,
 	.setup_hold_time_hs_mode = 0x0,
 	.has_interface_timing_reg = true,
+	.has_hs_mode_support = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra210_i2c_hw = {
@@ -1602,6 +1630,7 @@ static const struct tegra_i2c_hw_feature tegra210_i2c_hw = {
 	.setup_hold_time_fast_fast_plus_mode = 0,
 	.setup_hold_time_hs_mode = 0,
 	.has_interface_timing_reg = true,
+	.has_hs_mode_support = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra186_i2c_hw = {
@@ -1627,6 +1656,7 @@ static const struct tegra_i2c_hw_feature tegra186_i2c_hw = {
 	.setup_hold_time_fast_fast_plus_mode = 0,
 	.setup_hold_time_hs_mode = 0,
 	.has_interface_timing_reg = true,
+	.has_hs_mode_support = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra194_i2c_hw = {
@@ -1648,10 +1678,13 @@ static const struct tegra_i2c_hw_feature tegra194_i2c_hw = {
 	.thigh_std_mode = 0x7,
 	.tlow_fast_fastplus_mode = 0x2,
 	.thigh_fast_fastplus_mode = 0x2,
+	.tlow_hs_mode = 0x8,
+	.thigh_hs_mode = 0x3,
 	.setup_hold_time_std_mode = 0x08080808,
 	.setup_hold_time_fast_fast_plus_mode = 0x02020202,
 	.setup_hold_time_hs_mode = 0x090909,
 	.has_interface_timing_reg = true,
+	.has_hs_mode_support = true,
 };
 
 static const struct tegra_i2c_hw_feature tegra256_i2c_hw = {
-- 
2.43.0

[PATCH v7 3/4] i2c: tegra: Add support for SW mutex register

[Kartik Rajput]

Add support for SW mutex register introduced in Tegra264 to provide
an option to share the interface between multiple firmwares and/or
VMs. This involves following steps:

 - A firmware/OS writes its unique ID to the mutex REQUEST field.
 - Ownership is established when reading the GRANT field returns the
   same ID.
 - If GRANT shows a different non-zero ID, the firmware/OS retries
   until timeout.
 - After completing access, it releases the mutex by writing 0.

However, the hardware does not ensure any protection based on the
values. The driver/firmware should honor the peer who already holds
the mutex.

Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
---
v6 -> v7:
	* Return bool from tegra_i2c_mutex_acquired() and
	  tegra_i2c_mutex_trylock() functions.
	* Move `has_mutex` check inside tegra_i2c_mutex_lock/unlock
	  functions.
	* Remove redundant empty line added in tegra_i2c_xfer() in v6.
	* Fix pm_runtime_put() not getting called if mutex unlock fails.
	* In tegra_i2c_mutex_lock() simplify the logic to check if the
	  mutex is acquired or not by checking the value of `ret`
	  variable.
	* Update commit message to describe the functioning of SW mutex
	  feature.
v4 -> v6:
	* Guard tegra_i2c_mutex_lock() and tegra_i2c_mutex_unlock() to
	  ensure that they are called on platforms which support SW
	  mutex. 
v3 -> v4:
	* Update timeout logic of tegra_i2c_mutex_lock() to use
	  read_poll_timeout APIs for improving timeout logic.
	* Add tegra_i2c_mutex_acquired() to check if mutex is acquired
	  or not.
	* Rename I2C_SW_MUTEX_ID as I2C_SW_MUTEX_ID_CCPLEX.
	* Function tegra_i2c_poll_register() was moved unnecessarily, it
	  has now been moved to its original location.
	* Use tegra_i2c_mutex_lock/unlock APIs in the tegra_i2c_xfer()
	  function. This ensures proper propagation of error in case
	  mutex lock fails.
	  Please note that as the function tegra_i2c_xfer() is
	  already guarded by the bus lock operation there is no need of
	  additional lock for the tegra_i2c_mutex_lock/unlock APIs.
v2 -> v3:
	* Update tegra_i2c_mutex_trylock and tegra_i2c_mutex_unlock to
	  use readl and writel APIs instead of i2c_readl and i2c_writel
	  which use relaxed APIs.
	* Use dev_warn instead of WARN_ON if mutex lock/unlock fails.
v1 -> v2:
	* Fixed typos.
	* Fix tegra_i2c_mutex_lock() logic.
	* Add a timeout in tegra_i2c_mutex_lock() instead of polling for
	  mutex indefinitely.
---
 drivers/i2c/busses/i2c-tegra.c | 92 ++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 6f816de8b3af..bd254f5465f8 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -137,6 +137,14 @@
 
 #define I2C_MASTER_RESET_CNTRL			0x0a8
 
+#define I2C_SW_MUTEX				0x0ec
+#define I2C_SW_MUTEX_REQUEST			GENMASK(3, 0)
+#define I2C_SW_MUTEX_GRANT			GENMASK(7, 4)
+#define I2C_SW_MUTEX_ID_CCPLEX			9
+
+/* SW mutex acquire timeout value in microseconds. */
+#define I2C_SW_MUTEX_TIMEOUT_US			(25 * USEC_PER_MSEC)
+
 /* configuration load timeout in microseconds */
 #define I2C_CONFIG_LOAD_TIMEOUT			1000000
 
@@ -210,6 +218,7 @@ enum msg_end_type {
  * @has_interface_timing_reg: Has interface timing register to program the tuned
  *		timing settings.
  * @has_hs_mode_support: Has support for high speed (HS) mode transfers.
+ * @has_mutex: Has mutex register for mutual exclusion with other firmwares or VMs.
  */
 struct tegra_i2c_hw_feature {
 	bool has_continue_xfer_support;
@@ -237,6 +246,7 @@ struct tegra_i2c_hw_feature {
 	u32 setup_hold_time_hs_mode;
 	bool has_interface_timing_reg;
 	bool has_hs_mode_support;
+	bool has_mutex;
 };
 
 /**
@@ -381,6 +391,76 @@ static void i2c_readsl(struct tegra_i2c_dev *i2c_dev, void *data,
 	readsl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg), data, len);
 }
 
+static bool tegra_i2c_mutex_acquired(struct tegra_i2c_dev *i2c_dev)
+{
+	unsigned int reg = tegra_i2c_reg_addr(i2c_dev, I2C_SW_MUTEX);
+	u32 val, id;
+
+	val = readl(i2c_dev->base + reg);
+	id = FIELD_GET(I2C_SW_MUTEX_GRANT, val);
+
+	return id == I2C_SW_MUTEX_ID_CCPLEX;
+}
+
+static bool tegra_i2c_mutex_trylock(struct tegra_i2c_dev *i2c_dev)
+{
+	unsigned int reg = tegra_i2c_reg_addr(i2c_dev, I2C_SW_MUTEX);
+	u32 val, id;
+
+	val = readl(i2c_dev->base + reg);
+	id = FIELD_GET(I2C_SW_MUTEX_GRANT, val);
+	if (id != 0 && id != I2C_SW_MUTEX_ID_CCPLEX)
+		return false;
+
+	val = FIELD_PREP(I2C_SW_MUTEX_REQUEST, I2C_SW_MUTEX_ID_CCPLEX);
+	writel(val, i2c_dev->base + reg);
+
+	return tegra_i2c_mutex_acquired(i2c_dev);
+}
+
+static int tegra_i2c_mutex_lock(struct tegra_i2c_dev *i2c_dev)
+{
+	int locked;
+	int ret;
+
+	if (!i2c_dev->hw->has_mutex)
+		return 0;
+
+	if (i2c_dev->atomic_mode)
+		ret = read_poll_timeout_atomic(tegra_i2c_mutex_trylock, locked, locked,
+					       USEC_PER_MSEC, I2C_SW_MUTEX_TIMEOUT_US,
+					       false, i2c_dev);
+	else
+		ret = read_poll_timeout(tegra_i2c_mutex_trylock, locked, locked, USEC_PER_MSEC,
+					I2C_SW_MUTEX_TIMEOUT_US, false, i2c_dev);
+
+	if (ret)
+		dev_warn(i2c_dev->dev, "failed to acquire mutex\n");
+
+	return ret;
+}
+
+static int tegra_i2c_mutex_unlock(struct tegra_i2c_dev *i2c_dev)
+{
+	unsigned int reg = tegra_i2c_reg_addr(i2c_dev, I2C_SW_MUTEX);
+	u32 val, id;
+
+	if (!i2c_dev->hw->has_mutex)
+		return 0;
+
+	val = readl(i2c_dev->base + reg);
+
+	id = FIELD_GET(I2C_SW_MUTEX_GRANT, val);
+	if (id && id != I2C_SW_MUTEX_ID_CCPLEX) {
+		dev_warn(i2c_dev->dev, "unable to unlock mutex, mutex is owned by: %u\n", id);
+		return -EPERM;
+	}
+
+	writel(0, i2c_dev->base + reg);
+
+	return 0;
+}
+
 static void tegra_i2c_mask_irq(struct tegra_i2c_dev *i2c_dev, u32 mask)
 {
 	u32 int_mask;
@@ -1422,6 +1502,10 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 		return ret;
 	}
 
+	ret = tegra_i2c_mutex_lock(i2c_dev);
+	if (ret)
+		return ret;
+
 	for (i = 0; i < num; i++) {
 		enum msg_end_type end_type = MSG_END_STOP;
 
@@ -1451,6 +1535,7 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 			break;
 	}
 
+	ret = tegra_i2c_mutex_unlock(i2c_dev);
 	pm_runtime_put(i2c_dev->dev);
 
 	return ret ?: i;
@@ -1527,6 +1612,7 @@ static const struct tegra_i2c_hw_feature tegra20_i2c_hw = {
 	.setup_hold_time_hs_mode = 0x0,
 	.has_interface_timing_reg = false,
 	.has_hs_mode_support = false,
+	.has_mutex = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra30_i2c_hw = {
@@ -1553,6 +1639,7 @@ static const struct tegra_i2c_hw_feature tegra30_i2c_hw = {
 	.setup_hold_time_hs_mode = 0x0,
 	.has_interface_timing_reg = false,
 	.has_hs_mode_support = false,
+	.has_mutex = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra114_i2c_hw = {
@@ -1579,6 +1666,7 @@ static const struct tegra_i2c_hw_feature tegra114_i2c_hw = {
 	.setup_hold_time_hs_mode = 0x0,
 	.has_interface_timing_reg = false,
 	.has_hs_mode_support = false,
+	.has_mutex = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra124_i2c_hw = {
@@ -1605,6 +1693,7 @@ static const struct tegra_i2c_hw_feature tegra124_i2c_hw = {
 	.setup_hold_time_hs_mode = 0x0,
 	.has_interface_timing_reg = true,
 	.has_hs_mode_support = false,
+	.has_mutex = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra210_i2c_hw = {
@@ -1631,6 +1720,7 @@ static const struct tegra_i2c_hw_feature tegra210_i2c_hw = {
 	.setup_hold_time_hs_mode = 0,
 	.has_interface_timing_reg = true,
 	.has_hs_mode_support = false,
+	.has_mutex = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra186_i2c_hw = {
@@ -1657,6 +1747,7 @@ static const struct tegra_i2c_hw_feature tegra186_i2c_hw = {
 	.setup_hold_time_hs_mode = 0,
 	.has_interface_timing_reg = true,
 	.has_hs_mode_support = false,
+	.has_mutex = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra194_i2c_hw = {
@@ -1685,6 +1776,7 @@ static const struct tegra_i2c_hw_feature tegra194_i2c_hw = {
 	.setup_hold_time_hs_mode = 0x090909,
 	.has_interface_timing_reg = true,
 	.has_hs_mode_support = true,
+	.has_mutex = false,
 };
 
 static const struct tegra_i2c_hw_feature tegra256_i2c_hw = {
-- 
2.43.0

[PATCH v7 4/4] i2c: tegra: Add Tegra264 support

[Kartik Rajput]

From: Akhil R <akhilrajeev@nvidia.com>

Add support for Tegra264 SoC which supports 17 generic I2C controllers,
two of which are in the AON (always-on) partition of the SoC. In
addition to the features supported by Tegra194 it also supports a
SW mutex register to allow sharing the same I2C instance across
multiple firmware.

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
---
v1 -> v4:
	* Update commit message to mention the SW mutex feature
	  available on Tegra264.
---
 drivers/i2c/busses/i2c-tegra.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index bd254f5465f8..538711120976 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -1804,7 +1804,36 @@ static const struct tegra_i2c_hw_feature tegra256_i2c_hw = {
 	.has_interface_timing_reg = true,
 };
 
+static const struct tegra_i2c_hw_feature tegra264_i2c_hw = {
+	.has_continue_xfer_support = true,
+	.has_per_pkt_xfer_complete_irq = true,
+	.clk_divisor_hs_mode = 1,
+	.clk_divisor_std_mode = 0x1d,
+	.clk_divisor_fast_mode = 0x15,
+	.clk_divisor_fast_plus_mode = 0x8,
+	.has_config_load_reg = true,
+	.has_multi_master_mode = true,
+	.has_slcg_override_reg = true,
+	.has_mst_fifo = true,
+	.quirks = &tegra194_i2c_quirks,
+	.supports_bus_clear = true,
+	.has_apb_dma = false,
+	.tlow_std_mode = 0x8,
+	.thigh_std_mode = 0x7,
+	.tlow_fast_fastplus_mode = 0x2,
+	.thigh_fast_fastplus_mode = 0x2,
+	.tlow_hs_mode = 0x4,
+	.thigh_hs_mode = 0x2,
+	.setup_hold_time_std_mode = 0x08080808,
+	.setup_hold_time_fast_fast_plus_mode = 0x02020202,
+	.setup_hold_time_hs_mode = 0x090909,
+	.has_interface_timing_reg = true,
+	.has_hs_mode_support = true,
+	.has_mutex = true,
+};
+
 static const struct of_device_id tegra_i2c_of_match[] = {
+	{ .compatible = "nvidia,tegra264-i2c", .data = &tegra264_i2c_hw, },
 	{ .compatible = "nvidia,tegra256-i2c", .data = &tegra256_i2c_hw, },
 	{ .compatible = "nvidia,tegra194-i2c", .data = &tegra194_i2c_hw, },
 	{ .compatible = "nvidia,tegra186-i2c", .data = &tegra186_i2c_hw, },
-- 
2.43.0